Stressed woman wearing surgical mask

Know Your Health: Is Anxiety Genetic?

By LunaDNA Contributing Writer 

Many people experience anxiety during their lifetime. However, anxiety is not normal if it takes over your life.

A genetic predisposition for anxiety can trigger an over-the-top response to a low-key event. There are many risk factors for anxiety disorders including genetics, personality, brain chemistry, and external influences.  

Learn more about anxiety, including:   

  • What is Anxiety?
  • Types of Anxiety Disorders
  • Symptoms of Anxiety
  • What Causes Anxiety?
  • Is Anxiety Genetic?
  • Is Anxiety Hereditary?
  • Anxiety Diagnosis

Generalized Anxiety Disorder 

Generalized anxiety disorder is a chronic condition characterized by incessant and excessive worrying. A person with this disorder expects the worst, even when there is no plausible reason to do so. Feeling anxious for no reason is a common sentiment for those with this condition.  

According to the National Institute of Mental Health, generalized anxiety disorder sometimes runs in families. It’s unknown why some family members have it while others do not. The specific cause is unknown, but it is suspected that it’s a combination of family history, biological factors, and stressful life experiences.  

Symptoms may include: 

  • worrying too much
  • feeling nervous
  • feeling restless
  • difficulty concentrating
  • being easily startled
  • having insomnia
  • feeling exhausted
  • feeling irritable
  • sweating
  • feeling light-headed
  • feeling out of breath
  • difficulty swallowing
  • trembling
  • having to go to the bathroom frequently
  • having headaches
  • having stomach aches

Treatment by a doctor may include therapy and/or medication. 

Panic Disorder & Panic Attacks 

Panic attacks are recurring sudden attacks of terror that often come with debilitating physical symptoms. The episodes can last minutes or hours. A trigger may bring on the attacks, but often they arise for seemingly no reason. Symptoms include accelerated heart rate, trembling or shaking, having trouble breathing, sweating, feeling out of control, or feeling doomed. Because panic attacks are traumatic, some people with this disorder constantly worry when the next attack will occur and avoid places or situations. This can lead to another anxiety disorder called agoraphobia, which is the fear and avoidance of certain places or situations that might make you feel helpless or embarrassed. 

If left untreated, panic attacks can turn into a panic disorder. This occurs when a panic attack is followed up with a month or more of intense and constant worrying about the next panic attack and the fallout from it. However, not everyone that has panic attacks has a panic disorder. Treatment by a doctor for both conditions may include therapy and/or medication. 

Social Anxiety Disorder 

People with social anxiety disorder fear being in social or performance situations in which they might be judged negatively or be embarrassed. While it’s normal to get stage fright, people with this disorder tend to avoid public situations and human contact.  

Symptoms include blushing, accelerated heartbeat, sweating, trembling, nausea, lightheadedness, trouble breathing, and muscle tension. A typical response to this anxiety disorder is to avoid social situations whenever possible. Treatment by a doctor may include therapy and/or medication. 

Symptoms of Anxiety 

Although there are various types of anxiety disorders, many signs and symptoms of the types are similar including:  

  • accelerated heart rate
  • hyperventilation
  • sweating
  • shaking
  • sense of doom or panic
  • nervousness
  • restlessness
  • tension
  • tiredness
  • difficulty concentrating
  • insomnia
  • gastrointestinal issues
  • inability to stop worrying
  • having trouble controlling urge to avoid trigger events

Is Anxiety Genetic? 

Several parts of the brain play a role in fear and anxiety, so its genetic connections are complex. Through continued research, collecting data, and by learning more about how the brain functions in particular anxiety disorders, researchers can help create better treatments.  

Anxiety can be triggered by certain external events, and people with certain predispositions may be wired to react anxiously. It is possible that both genetic and environmental factors contribute to an anxiety disorder.  

While the link between genetics and anxiety is still unclear, it has been shown that anxiety disorders run in families. Genetically-linked brain disorders are complex, and more research needs to be done to truly understand whether or not anxiety is hereditary. 

Anxiety Diagnosis  

Diagnosing anxiety can be complex, so it is important to see a doctor or psychiatrist to get properly evaluated. A doctor may start with a physical exam to see if there is an underlying condition causing the anxiety. Laboratory testing of blood and urine samples may also be needed to rule out other possible causes. The doctor will look at medical history and ask questions to determine the proper diagnosis. If you experience some or all of the symptoms of anxiety, consult your physician. 

Treatments for Anxiety 

Treatments for anxiety vary largely based on the type of anxiety, root cause, and each individual’s situation and symptoms. A doctor decides how to treat patients based on what they need to function better in daily life. Two primary avenues of treatment are most common: recommended therapy to relieve stress and the use of anti-anxiety medication. Depending on the severity of an individual’s anxiety, a physician may recommend both therapy and medication as the best treatment.  

The field of pharmacogenomics, the study of how gene’s affect drug response, is making great strides in identifying which medications and dosages work better based on a patient’s genetic makeup. However, more research is needed to understand exactly how genetics plays a role in anxiety disorders and brain chemistry. As research continues, meaningful scientific breakthroughs will lead to better prevention and treatment of anxiety disorders. 

If you’d like to help researchers better understand anxiety and other genetic disorders, take the LunaDNA mental wellness survey. The more people who come together to contribute health data for the greater good, the quicker and more efficient research will scale, and improve the quality of life for us all.  

Click here to get started.

Is Lactose Intolerance Genetic

Is Lactose Intolerance Genetic? | How to Know If You’re Lactose Intolerant

Lactose intolerance has both genetic and non-genetic causes. Lactose intolerance can happen at any age. Learn the basics of lactose intolerance and how it could affect your health.

People with lactose intolerance are unable to fully digest sugars found in dairy products. There are many reasons people become lactose intolerant, and genetics may play a role.  According to the U.S. National Library of Medicine, about 65 percent of the world population (or nearly 5 billion people) are lactose intolerant. In East Asia, the number is more than 90 percent.

Know Your Health: The Genetics of Lactose Intolerance

Lactose intolerance is the inability to eat dairy without having an adverse reaction. It occurs when the body doesn’t produce enough of an enzyme that aids in the digestion of sugars found in dairy. Learn about the different types of lactose intolerance, genetic disposition, how it is diagnosed, and how to manage it with this guide:

  • What is Lactose Intolerance?
    • Types of Lactose Intolerance
    • Lactose Intolerance Symptoms
    • Am I Lactose Intolerant?
  • What Causes Lactose Intolerance?
    • Is Lactose Intolerance Genetic?
    • Is Lactose Intolerance Inherited?
    • Can You Become Lactose Intolerant?
    • Lactose Intolerance Risk Factors
  • Lactose Intolerance Test — How It’s Diagnosed
    • Lactose Intolerance Management

What is Lactose Intolerance?

Lactose intolerance is the inability to fully digest sugars found in dairy products. Lactase is an enzyme produced in the small intestine that breaks down sugars in dairy products into the simple sugars glucose and galactose, which are absorbed into the bloodstream as fuel. Lactose-intolerant people do not generate enough lactase for the process to work.

With lactase in low production, the undigested lactose passes into the colon where it interacts with bacteria. This interaction causes the typical symptoms of lactose intolerance, which are bloating, gas, stomach cramps, diarrhea, nausea, and sometimes vomiting.

Milk allergies, while similar, are less common and have symptoms with the potential to be far more severe with violent vomiting, bloody stools, and anaphylactic shock. Milk allergies often appear early in life, while lactose intolerance generally appears in adulthood.

Types of Lactose Intolerance

There are four distinct types of lactose intolerance. Two are genetically predisposed, one is often temporary, and the fourth is usually brought on by illness or injury.

  • Primary lactose intolerance is the most common type. Most people with primary lactose intolerance are genetically predisposed to significantly reduce lactase production between the ages of 2 and 5. As enzyme levels decrease, dairy becomes harder to digest and symptoms arise. Symptoms may not show until adulthood.
  • Secondary lactose intolerance is caused by an injury or illness. Any negative impact to the small intestine can cause less production of lactase. Diseases, such as Crohn’s and celiac, are commonly linked to this type of lactose intolerance. Surgery, medication, or chemotherapy can also hinder production of the enzyme. This type of lactose intolerance can be temporary or permanent.
  • Developmental lactose intolerance occurs in babies who are born prematurely. It usually resolves after the baby’s small intestines are fully developed.
  • Congenital lactose intolerance is the rarest type. It occurs when a baby is born with little to no lactase production in the small intestine. This genetic disorder can only be passed to a baby if both parents have the mutated gene.

Lactose Intolerance Symptoms

Symptoms and severity vary depending on the type of lactose intolerance and how much dairy was consumed. Typically, the following symptoms hit within a few hours of ingesting dairy:

  • Stomach cramps
  • Bloating
  • Diarrhea
  • Gas
  • Nausea
  • Pain in the abdomen
  • Vomiting
  • Stomach rumbling

Am I Lactose Intolerant?

People who experience any of the symptoms listed above after eating dairy may be lactose intolerant. Whether you have one of the symptoms or all of them, you should seek medical treatment or advice from a physician if you are uncomfortable or over-the-counter medications do not work.

What Causes Lactose Intolerance?

The most common type of lactose intolerance, primary lactose intolerance, is the result of an inherited genetic trait that runs in families. When a baby stops breastfeeding, the genetic response is to decrease the expression of the LCT gene, which provides instructions for making lactase in the small intestine. When lactase-producing cells line the walls of the small intestine, they help absorb nutrients as food passes through. Without this enzyme, lactose is broken down by bacteria inside the colon, which causes the symptoms of lactose intolerance.

Is Lactose Intolerance Genetic?

The type of lactose intolerance a person suffers from determines whether genes play a role or not. For primary lactose intolerance, the most common form, genetics do play a role. Located within chromosome 2, the MCM6 gene helps control the activity or expression of the LCT gene.

The ability to tolerate lactose depends on the type of MCM6 variant a person has. The LCT gene follows the instructions provided by MCM6 and either produces adequate lactase to digest milk or not enough. For babies born with congenital lactose intolerance, the MCM6 gene is responsible to little or no lactase production at birth.

Can You Become Lactose Intolerant?

Lactose intolerance can be triggered by injury, illness, medication, or surgery. Any negative impact to the small intestine can trigger lactose intolerance. This type of lactose intolerance can be temporary or permanent. Primary lactose intolerance can set in later in life, usually once an individual reaches adulthood.

Lactose Intolerance Risk Factors

Lactose intolerance can happen at any time for a myriad of reasons. For example, taking antibiotics or having a bout of diarrhea can interfere with the small intestine’s ability to produce lactase. Below are the most common risk factors associated with having any of the four forms of lactose intolerance:

  • Crohn’s disease
  • Celiac disease
  • Injury
  • Surgery
  • Aging
  • Medication
  • Chemotherapy
  • Antibiotics
  • Diarrhea

Lactose Intolerance Test — How It’s Diagnosed

If you get the same symptoms after consuming dairy products, you should discuss the symptoms with your doctor. A doctor can administer a hydrogen breath test. Normally, hydrogen gas is barely detectable in the breath, but if you are lactose intolerant, you will have undigested dairy products fermenting in the colon, which produce hydrogen. The test takes about two to three hours and begins with drinking a lactose-heavy beverage. Afterwards, the patient’s breath is analyzed at regular intervals to determine the amount of hydrogen. Hydrogen is detectable at higher levels if someone is lactose intolerant.

Genetic tests are also available to analyze some forms of lactose intolerance. Additionally, a doctor can do more invasive procedures, such as an endoscopy, to view the inside of the intestines with a camera or take tissue samples from the inside of the gut.

Lactose Intolerance Management

While there is no cure for lactose intolerance, there are successful ways to manage the condition. The simplest way is to avoid dairy products that trigger bouts of discomfort. It’s still possible for some lactose-intolerant people to eat dairy products on occasion if a few rules are followed to avoid discomfort.

Eating small amounts of dairy products with other non-lactose foods can sometimes help you successfully deal with the side effects. The type of lactose-rich foods chosen can make a difference. Yogurt is generally easier to digest than milk. Supplements that help digest lactose are also available to take before eating dairy. Be sure to consult a doctor before adding any supplements to a diet.

Although great strides have been made in deciphering the genetics of lactose intolerance, more research needs to be done to better understand how to treat and manage the condition. As we understand more about the genetics of the human body, new research will lead to scientific breakthroughs to help people with lactose intolerance. You can directly contribute to health research with your unique health data, which enables the research needed to find treatments and cures to not only lactose intolerance, but other ailments as well.

What is Diabetes?

What is Diabetes? | Major Diabetes Risk Factors & Prevention

Is diabetes hereditary or acquired? What are the major risk factors of diabetes? Learn about diabetes, how to test for the disease, and prevention strategies.

If you’ve ever taken a home DNA kit, it’s likely that you were told it can measure the risk of developing a particular disease, like diabetes. But in fact, there’s only so much DNA kits can tell you about whether or not diabetes is in your present or future, as risks of such diseases come from many sources, not just genetic changes. Although valid studies are necessary to prove these tests provide accurate results, there’s one thing we do know for certain — your understanding of disease and overall health plays a vital role the quality of your life.

In 2017, the Centers for Disease Control and Prevention (CDC) reported that diabetes and prediabetes affects more than 100 million U.S. adults. Although there is currently no cure for diabetes, there are treatments that can support people living with the disease.

Know Your Health: What Is Diabetes & Diabetes Risk Factors

Diabetes mellitus is more commonly known as diabetes and refers to the various groups of metabolic disorders, all of which affect how the body uses blood sugar, or glucose. There are multiple types of diabetes, but all involve excess sugar in the blood due to an abnormal metabolism of carbohydrates. When too much sugar remains in the blood, it causes multiple health complications. There are several types of diabetes, and while they all have similarities, they are also very different in terms of nuances, risk factors, and treatment options. Learn more about diabetes, prevention, and treatment by reading this guide.

  • What is Diabetes?
    • What Are the Different Types of Diabetes?
  • What Causes Diabetes?
    • Is Diabetes Genetic?
    • Is Diabetes Hereditary?
    • Diabetes Risk Factors
    • How to Prevent Diabetes
  • Diabetes Diagnosis — How to Test for Diabetes
    • What is the Treatment for Diabetes?

What is Diabetes?

When you have diabetes, your blood sugar, or blood glucose, is too high. Blood sugar is the primary source of energy that comes directly from the foods we eat. The pancreas makes a hormone called insulin, which helps glucose get into cells so it can be used for energy. When the body doesn’t make enough insulin, glucose can’t reach your cells so it builds up in your blood. The causes of diabetes vary by types but they all result in excess sugar in the blood, which can lead to serious health problems if not corrected.

What Are the Different Types of Diabetes?

While there are several types of diabetes, the three that are most common are Type 1, Type 2, and gestational. Other less common types include monogenic and cystic fibrosis-related diabetes.

Type 1 Diabetes

Type 1 diabetes occurs when your body isn’t making insulin because your immune system is attacking and destroying the insulin-making cells in your pancreas. If you’re diagnosed with Type 1, you need to take insulin every day. While Type 1 diabetes is typically diagnosed at a younger age in children or young adults, it can onset at any age.

Type 2 Diabetes

Type 2 diabetes occurs when your body makes insulin, but it doesn’t make or use it well. This is the most common type of diabetes. When you have Type 2 diabetes, cells develop a resistance to the action of insulin, and as a result, your pancreas can’t keep up insulin production to keep your blood glucose level in a healthy range. Similarly to Type 1, sugar can’t move into cells and instead builds up in the bloodstream.

Type 2 diabetes can be diagnosed at any age. However, it is most often diagnosed during middle or older age.

Gestational Diabetes

Gestational diabetes can occur during pregnancy, but often will go away after giving birth. However, if you develop gestational diabetes while pregnant, you are more likely to develop Type 2 diabetes later in life.

Monogenic Diabetes

Monogenic diabetes is a rare type of diabetes that is inherited and results from single gene mutations, as opposed to Types 1 and 2, which are caused by multiple genes. The gene mutations are often passed from parent to child, but they can occasionally occur spontaneously.

The two most common types of monogenic diabetes are neonatal and maturity-onset diabetes of the young (MODY).

What Causes Diabetes?

Diabetes is caused by various factors depending on the type you have. Yet, despite the different causes, there are two important factors in all diabetes diagnoses: an inherited predisposition to the disease and an environmental trigger.

Type 1 Diabetes — While the exact cause of Type 1 diabetes is unknown, it’s believed that a combination of environmental factors (like viruses) and genetic susceptibility come into play. What is known is that Type 1 occurs when your immune system attacks or destroys the cells that produce insulin in the pancreas. Being overweight does not appear to be a factor in Type 1 diabetes.

Type 2 Diabetes — The most common of all types, Type 2 diabetes is caused by genes and lifestyle factors, among other things. Family history, weight or obesity, and physical inactivity are also significant contributing factors. Most often, Type 2 diabetes starts with insulin resistance, which occurs when your body doesn’t process insulin well. The pancreas tries to make more insulin, but eventually cannot meet demand. Once this happens, your blood glucose levels rise.

Gestational Diabetes — Gestational diabetes is caused by hormonal changes that women experience throughout their pregnancy. Sometimes, these changes make cells more resistant to insulin. The pancreas tries to produce more insulin but is unable to do so adequately, and glucose stays in the blood rather than going to cells. Genetics and lifestyle can also play a role in whether or not a woman will develop diabetes during pregnancy.

Is Diabetes Genetic?

The genetic component of diabetes is complicated. With Type 1 diabetes, most people inherit risk factors from both of their parents. For example:

  • A male with Type 1 diabetes has a 1 in 17 chance of his child developing the disease.
  • A woman with Type 1 who has a child before age 25 will have a 1 in 25 chance of having a child with diabetes.
  • A woman with Type 1 who has a child after age 25 will have a 1 in 100 chance of having a child with diabetes.
  • If you were diagnosed before 11 years of age, your future child’s risk is doubled.
  • If both you and your partner have Type 1 diabetes, your children will have between a 1 in 10 and 1 in 4 chance of developing the disease.

If you have Type 1 and are Caucasian, it is likely you have a gene called HLA-DR3 or HLA-DR4, and if you share these genes with your child, he or she is at greater risk. Research done for other ethnicity groups has had similar findings, but are not as well-studied. The HLA-DR7 and HLA-DR9 genes may put African Americans and Japanese, respectively, at greater risk. Current research is aimed at predicting and understanding the odds of a child developing diabetes in relation to race, gender, and other factors.

Type 2 diabetes has a stronger link to family history but environmental factors play more of a role in this type. Twin studies have shown a strong connection in the development of Type 2 but environmental factors, such as obesity and exercise habits, also tend to run in families. If you have Type 2 diabetes, most likely it is due to both lifestyle and genetic factors. However, studies show that by exercising and losing weight, you can delay or prevent onset of Type 2 diabetes.

Diabetes Risk Factors

While we’ve examined how some risk factors might be inherited, other risks can be avoided with the right care and precautionary measures taken. Some of the top risk factors to note include, in no order of importance:

  • Inactivity
  • Weight
  • Poor diet
  • Age
  • Family history
  • Race
  • High blood pressure
  • Previous history of gestational diabetes

How to Prevent Diabetes

While Type 1 diabetes cannot be prevented, there are multiple approaches that can be taken to reduce your risk of developing Type 2, with healthy lifestyle choices at the top of the list.

Eating healthy foods that are high in fiber and low in fat and calories is important. Whole grains, fruits, and vegetables are great snack choices. In addition to a healthy diet, being sure to get plenty of physical exercise and losing weight are both critical if you are high risk. Just 30 minutes a day, at least five days a week, of moderate activity like a brisk walk, bike ride, or swim can make a huge difference in reducing your risk of developing Type 2 diabetes.

Diabetes Diagnosis — How to Test for Diabetes

Multiple tests are used by a doctor to make a diagnosis of diabetes. A glycated hemoglobin, or A1C test, can indicate average blood sugar levels from the past several months. The A1C is a blood test that measures the percentage of blood sugar attached to hemoglobin, which is the protein that carries oxygen in red blood cells. A1C results can indicate the following:

  • 6.5 percent or higher — indication of diabetes; must be in this range on two separate test results
  • 5.7-6.4 percent — indication of prediabetes
  • 5.6 percent or lower — considered normal; no indication of diabetes

Other tests include a random blood sugar test that doesn’t account for last meals (meaning, no fasting is necessary) or a fasting blood sugar test that’s administered after an overnight fast. Another test administered is an oral glucose tolerance test (OGTT), in which you fast overnight and your baseline blood sugar level is recorded in the morning, and again two hours after you ingest a sugary drink. The OGTT helps your doctor determine how your body processes sugar.

If a doctor suspects Type 1 diabetes, a urine test will be able to detect any presence of ketones, a byproduct that’s produced when fat breaks down. Another test that is used looks for destructive immune system cells called autoantibodies.

Common symptoms of diabetes include:

  • Excessive and increased thirst
  • Dry mouth
  • Numbness or tingling in the hands or feet
  • Extreme hunger, particularly after eating
  • Unexplained weight loss despite regular eating
  • Frequent urination
  • Fatigue or feeling weak
  • Blurred vision
  • Irritability
  • Sores that won’t heal or are slow-healing
  • Gum or skin infections

What is the Treatment for Diabetes?

Managing a diabetes diagnosis is different depending on the type of diabetes you have. But in all cases, diet and exercise are important.

Monitoring blood sugar, carbohydrate counting, and taking insulin and oral medications may all play a role in treatment. All people with Type 1 diabetes and many people with Type 2 diabetes require insulin injections or an insulin pump. Although some people with Type 2 diabetes manage their condition through diet and exercise alone, many patients need diabetes medications as well.

For women diagnosed with gestational diabetes, keeping blood sugar levels under control is imperative to keeping the baby healthy and avoiding complications during delivery. Treatment during pregnancy might include monitoring blood sugar levels and possibly using oral medications or insulin. In most cases, gestational diabetes will resolve after a woman gives birth; however, the risk of developing Type 2 later in life increases after a gestational diabetes diagnosis. Women who are diagnosed with gestational diabetes should be screened for diabetes at least every three years after their blood sugar levels return to normal.

Diabetes, while not yet a curable disease, is treatable. And with over 2,000 clinical trials investigating new interventions, there are many possibilities on the horizon. While medication and lifestyle can play a significant role in treatment, continued genetic research and advancements in precision, or personalized, medicine offer amazing hope for those living with diabetes.

How To Get Involved In Diabetes Research

In December 2018, the U.S. Securities and Exchange Commission approved LunaDNATM to offer shares of ownership in the organization in return for health data. This made LunaDNA the first community-owned health and DNA data platform to exist. Our goal is to build a rich and robust health discovery platform dedicated to supporting research, advancing science, and accelerating medical breakthroughs.

Now, for the first time, people affected by diabetes can contribute their health data to LunaDNA’s secure platform. By uploading a personal DNA data file or even just taking a health survey, you can directly contribute to health research. The more people who come together to contribute health data for the greater good, the quicker and more efficiently research will scale, improving the quality of life for us all.

Learn how you can directly contribute to health research at

Is Eye Color Genetic?

Is Eye Color Genetic? | What Your Eye Color Has to Do With Your History

Eye colors are passed down through generations, but sometimes genetic variations can lead to surprising results in eye colors. Learn about the genetics of eye color in this guide.

Whether eyes are blue or brown, eye color is determined by genetic traits handed down to children from their parents. A parent’s genetic makeup determines the amount of pigment, or melanin, in the iris of the his or her child’s eye. With high levels of brown melanin, the eyes look brown. With minimal levels of the same brown melanin, the eyes look blue. However, a genetic variation can cause a child’s eye color to be unpredictable, resulting in two blue-eyed parents having a brown-eyed child.

Know Your Health: Genetics of Eye Color

Eye colors have evolved over time and have roots in our ancestry. Although eye color is determined by genetic makeup, variations can cause different shades to appear. Learn more about the genetics of eye color, including:

  • How is Eye Color Determined?
    • Is Eye Color Genetic?
    • Is Eye Color Inherited?
    • Can Eye Color Be Predicted?
  • What Does Your Eye Color Mean?
    • Brown Eyes
    • Blue Eyes
    • Green Eyes
    • Hazel Eyes
  • How Does Your Eye Health Impact Your Life?

How Is Eye Color Determined?

Genetic makeup determines the amount of melanin in the eye. In eye color, there isn’t blue or green pigment. All eye colors have the same brown melanin incapable of refracting light. The difference in eye colors is due to the concentration and location of the brown melanin on the two layers of the iris. People with brown eyes have melanin on the back layer of the iris and some on the front layer, which absorbs more light and causes the iris to look brown. Eyes with no melanin on the front layer of the iris scatter light so that more blue light reflects out, so that the eyes appear blue.

The chromosomes a child inherits carry genetic information that determines eye color. Differences in the copies received from each parent causes variations in the amount of melanin produced. A region on chromosome 15 has a big part in determining eye color. The OCA2 and HERC2 genes are located in this region.

The OCA2 gene (formerly called the P gene) provides instructions for producing the P protein located in the melanocytes (specialized cells that produce melanin). If more protein is produced, then the eyes received more melanin, and eye color leans toward the brown end of the color spectrum. When less protein is produced, the eyes receive less melanin and eye color leans toward the blue end of the spectrum. Although nearly 75 percent of eye color is controlled by the OCA2 gene, other genes provide a pathway for melanin. These genes can raise or lower melanin levels, causing a child to have more or less melanin than either parent. These variations can result in blue-eyed parents having a brown-eyed child, or brown-eyed parents having a blue-eyed child. The former is more likely than the latter.

Is Eye Color Genetic?

Each cell in the human body normally contains 23 pairs of chromosomes. Chromosome 15 likely contains 600 to 700 genes integral to producing proteins. Two of these genes, OCA2 and HERC2, play a significant role in eye color selection.

Although the OCA2 gene produces the protein responsible for melanin, the HERC2 gene controls the OCA2 gene by turning its protein production on and off. The presence of at least one genetic variation in the HERC2 gene can reduce the amount of melanin produced, leading to lighter eyes. Other genes working with OCA2 and HERC2 have a smaller role, but on rare occasions override OCA2 to determine eye color.

Is Eye Color Inherited?

Eye color was once thought to be the result of a single hereditary trait. It was thought that each person received one eye color gene from each parent, and the dominant gene determined eye color. In this model, the brown-eye color gene was always dominant over the blue-eye color gene, and only two blue-eye color genes could color eyes blue.

Charles and Gertrude Davenport developed the dominant brown eye model in 1907. They suggested that blue eyes were caused by a single recessive gene, and blue-eyed parents could never produce a brown-eyed child. Dominant and recessive genes refer to inheritance patterns, and describe how likely it is for a certain trait to pass from parent to offspring.

Today, we know this model is simplistic, and that many genes determine that eye color. Although we can predict the color of a child’s eyes based on the parent’s eye colors, other genetic factors may alter the outcome.

Can Eye Color Be Predicted?

While it is possible to predict the probability of eye color, genetic factors may alter the outcome. Movie star Elizabeth Taylor’s parents probably did not predict their daughter’s rare violet eyes. Taylor’s eye color is thought to be the result of a genetic mutation in the FOXC2 gene, which causes a specific amount of melanin that produced a striking eye color and may cause double eye lashes as well as heart problems.

With eye color controlled by more than one gene, it is possible for a newborn to inherit any eye color. Predicting eye color is further complicated because it sometimes changes after birth. A baby’s blue eyes can turn brown as more melanin is deposited into the iris over the first three years of life.

What Does Your Eye Color Mean?

According to one theory, almost everyone (99.5 percent) with blue eyes might be able to trace their ancestry back to the same blue-eyed ancestor that lived in the northwest part of the Black Sea region some 6,000 to 10,000 years ago. This is based on the DNA analysis of about 800 blue-eyed people, in which only one person did not have the same blue-eye genetic mutation as the rest of the group. This mutation seems to have occurred during the Neolithic period (or New Stone Age) during the great agricultural migration to the northern part of Europe. Nearly all blue-eyed humans have this same mutation in the same location in their DNA. By contrast, brown-eyed humans have more variation in their DNA when it comes to eye color.

Brown Eyes

The majority of people in the world have brown eyes. The color brown is a result of a high concentration of melanin in the iris causing more light to be absorbed and less light to be reflected. Because of this, brown eyes are more naturally protected from the sun. This likely had evolutionary benefits similar to darker skin being able to withstand the hot sun longer. The genes responsible for skin color are closely linked to those that cause eye color.

Though brown eyes are the most common genetic eye color, there is more genetic variation among those with brown eyes than those with blue eyes. This may account for the variations of brown eye colors. These variations come from different genes on different chromosomes that carry genetic eye color information from our ancestors.

Blue Eyes

Originally, all humans had brown eyes. Some 6,000 to 10,000 years ago, a genetic mutation affecting one gene turned off the ability to produce enough melanin to color eyes brown causing blue eyes. This mutation arose in the OCA2 gene, the main gene responsible for determining eye color. Since blue eyes have survived throughout many generations, researchers think there may have been some evolutionary benefit, though the exact reason is unknown.

Blue eyes are the result of low concentrations of brown melanin, not blue pigmentation. Less melanin allows more light to reflect back to wavelengths on the blue color spectrum, which in turn make eyes appear blue. The reason why eyes are blue is the same reason the sky is blue. Some 8 to 10 percent of humans worldwide have blue eyes.

Green Eyes

Only about 2 percent of the world’s population has green eyes. Green eyes are a genetic mutation that produces low levels of melanin, but more than blue eyes. As in blue eyes, there is no green pigment. Instead, because of the lack of melanin in the iris, more light scatters out, which make the eyes appear green. Changes in light make lighter eyes look like they are changing colors like a chameleon.

Hazel Eyes

Hazel eyes are sometimes mistaken for green or brown eyes. They are not as rare as green eyes, but are rarer than blue eyes. Only about 5 percent of the population worldwide has the hazel eye genetic mutation. After brown eyes, they have the most melanin. . The combination of having less melanin (as with green eyes) and a lot of melanin (like brown eyes) make this eye color unique.

The color combinations in shades of green, brown, and gold are endless with hazel eyes, depending on the concentration of melanin. The light scatters as it does with blue and green eyes.  As with blue and green eyes, hazel eyes may appear to shift colors depending on the light. The eye color doesn’t actually shift, perception does. It is unknown if hazel eyes developed from brown eyes or green.

How does your eye health impact your life?

Your eye health may significantly impact your everyday life, from socializing with friends to driving at night. Share your eye health experiences to help scientists better understand your eyes’ impact on your daily life. Get started here.

The History of DNA

The History of DNA

By Contributing LunaDNA Writer. Last edited by LunaPBC on September 2019

The human hereditary material known as deoxyribonucleic acid, or DNA, is a long molecule containing the information organisms need to both develop and reproduce. DNA is found in every cell in the body, and is passed down from parent to child.

Although the discovery of DNA occurred in 1869 by Swiss-born biochemist Fredrich Miescher, it took more than 80 years for its importance to be fully realized. And even today, more than 150 years after it was first discovered, exciting research and technology continue to offer more insight and a better answer to the question: why is DNA important?  Learn more here about DNA, including:

  • What is DNA?
    ◦ What is DNA Made of?
    ◦ How Does DNA Work?
  • How Was DNA Discovered?
    ◦ Who Discovered DNA?
    ◦ When Was DNA Discovered?
  • The Future of DNA

What is DNA?

DNA is self-replicating material that’s in every living organism. In simplest terms, it is a carrier of all genetic information. It contains the instructions needed for organisms to develop, grow, survive, and reproduce. It’s one long molecule that contains our genetic “code,” or recipe. This recipe is the starting point for our development, but DNA’s interaction with outside influences such as our lifestyle, environment, and nutrition ultimately form the human being.

While most DNA is found in the nucleus of a cell, a small amount can also be found in the mitochondria, which generates energy so cells can function properly. Perhaps the most fascinating part of the process is the fact that nearly every cell in your body has the same DNA.

What is DNA Made of?

DNA is made up of molecules known as nucleotides. Each nucleotide contains a sugar and phosphate group as well as nitrogen bases. These nitrogen bases are further broken down into four types, including:

  • adenine (A)
  • cytosine (C)
  • guanine (G)
  • thymine (T)

DNA’s structure is a double-stranded helix, and it resembles the look of a twisted ladder. The sugar and phosphates are nucleotide strands that form the long sides. The nitrogen bases are the rungs. Every rung is actually two types of nitrogen bases that pair together to form a complete rung and hold the long strands of nucleotides together. Remember, there are four types of nitrogen bases, and they pair together specifically – adenine pairs with thymine, and guanine with cytosine.

Human DNA is unique in that it is made up of nearly 3 billion base pairs, and about 99 percent of them are the same in every human. However, it’s the sequence of these bases that determines what information is available to both build and maintain any organism.

Think of DNA like individual letters of the alphabet — letters combine with one another in a specific order and form to make up words, sentences, and stories. The same idea is true for DNA — how the nitrogen bases are ordered in DNA sequences forms the genes, which tell your cells how to make proteins. Ribonucleic acid (RNA), another type of nucleic acid, is formed during the process of transcription (when DNA is replicated). RNA’s function is to translate genetic information from DNA to proteins as it is read by a ribosome.

How Does DNA Work?

DNA is essentially a recipe for any living organism. It contains vital information that’s passed down from one generation to the next. DNA molecules within the nucleus of a cell wind tightly to form chromosomes, which help keep DNA secure and in place and store important information in the form of genes to determine an organism’s genetic information.

DNA works by copying itself into that single-stranded molecule called RNA. If DNA is the blueprint, you can think of RNA as the translator of instructions written in the blueprint.  During this process, DNA unwinds itself so it can be replicated. RNA is similar to DNA, but it does contain some significant molecular differences that set it apart. RNA acts as a messenger, carrying vital genetic information in a cell from DNA through ribosomes to create proteins, which then form all living things.

How Was DNA Discovered?

DNA was discovered in 1869 by Swiss researcher Friedrich Miescher, who was originally trying to study the composition of lymphoid cells (white blood cells). Instead, he isolated a new molecule he called nuclein (DNA with associated proteins) from a cell nucleus. While Miescher was the first to define DNA as a distinct molecule, several other researchers and scientists have contributed to our relative understanding of DNA as we know it today. And it wasn’t until the early 1940s that DNA’s role in genetic inheritance was even begun to be researched and understood.

Who Discovered DNA?

The full answer to the question who discovered DNA is complex, because in truth, many people have contributed to what we know about it. DNA was first discovered by Friedrich Miescher, but researchers and scientists continue to expound on his work to this day, as we are still learning more about its mysteries. As it turned out, Miescher’s discovery was just the beginning.

Credit for who first identified DNA is often mistakenly given to James Watson and Francis Crick, who actually just furthered Miescher’s discovery with their own groundbreaking research nearly 100 years later. Watson and Crick contributed largely to our understanding of DNA in terms of genetic inheritance, but much like Miescher, long before their work, others also made great advancements in and contributions to the field.

  • 1866 — Before the many significant discoveries and findings, Gregor Mendel, who is known as the “Father of Genetics,” was actually the first to suggest that characteristics are passed down from generation to generation. Mendel coined the terms we all know today as recessive and dominant.
  • 1869 — Friedrich Miescher identified the “nuclein” by isolating a molecule from a cell nucleus that would later become known as DNA.
  • 1881 — Nobel Prize winner and German biochemist Albrecht Kossel, who is credited with naming DNA, identified nuclein as a nucleic acid. He also isolated those five nitrogen bases that are now considered to be the basic building blocks of DNA and RNA: adenine (A), cytosine (C), guanine (G), and thymine (T) (which is replaced by uracil (U) in RNA).
  • 1882 — Shortly after Kossel’s findings, Walther Flemming devoted research and time to cytology, which is the study of chromosomes. He discovered mitosis in 1882 when he was the first biologist to execute a wholly systematic study of the division of chromosomes. His observations that chromosomes double is significant to the later-discovered theory of inheritance.
  • Early 1900s — Theodor Boveri and Walter Sutton were independently working on what’s now known as the Boveri-Sutton chromosome theory, or the chromosomal theory of inheritance. Their findings are fundamental in our understanding of how chromosomes carry genetic material and pass it down from one generation to the next.
  • 1902 — Mendel’s theories were finally associated with a human disease by Sir Archibald Edward Garrod, who published the first findings from a study on recessive inheritance in human beings in 1902. Garrod opened the door for our understanding of genetic disorders resulting from errors in chemical pathways in the body.
  • 1944 — Oswald Avery first outlined DNA as the transforming principle, which essentially means that it’s DNA, not proteins, that transform cell properties .
  • 1944-1950 — Erwin Chargaff discovered that DNA is responsible for heredity and that it varies between species. His discoveries, known as Chargaff’s Rules, proved that guanine and cytosine units, as well as adenine and thymine units, were the same in double-stranded DNA, and he also discovered that DNA varies among species.
  • Late 1940s — Barbara McClintock discovered the mobility of genes, ultimately challenging virtually everything that was once thought to be. Her discovery of the “jumping gene,” or the idea that genes can move on a chromosome, earned her the Nobel Prize in Physiology.
  • 1951 — Roslind Franklin’s work in X-ray crystallography began when she started taking X-ray diffraction photographs of DNA. Her images showed the helical form, which was confirmed by Watson and Crick nearly two years later. Her findings were only acknowledged posthumously.
  • 1953 — Watson and Crick published on DNA’s double helix structure that twists to form the ladder-like structure we think of when we picture DNA.

When Was DNA Discovered?

What we know about DNA today can be largely credited to James Watson and Francis Crick, who discovered the structure of DNA in 1953. Despite there being many important and contributing discoveries both before and after their work, this is the year they discovered DNA’s double helix, or spiraling, intertwined structure, which is fundamental to our current understanding of DNA as a whole.

The Future of DNA

The future of DNA has great potential. As researchers and scientists continue to advance what we know about the complexities of DNA and the insights it codes for, we can imagine a world with less and better-managed disease, longer life spans, and a personalized view of medicine that’s specifically applicable to individuals rather than the population as a whole.

DNA insights are already enabling the diagnosis and treatment of genetic diseases. Science is also hopeful that medicine will advance to be able to leverage the power of our own cells to fight disease.  For example, gene therapy is designed to introduce genetic material into cells to compensate for abnormal genes or to make a therapeutically beneficial protein.

Researchers also continue to use DNA sequencing technology to learn more about everything from combating infectious disease outbreaks to improving nutritional security.

Ultimately, DNA research will accelerate breaking the mold of the one-size-fits-all approach to medicine. Every new discovery in our understanding of DNA lends to further advancement in the idea of precision medicine, a relatively new way doctors are approaching healthcare through the use of genetic and molecular information to guide their approach to medicine. With precision or personalized medicine, interventions take into consideration the unique biology of the patient and are tailored individually to each patient, rather than being based on the predicted response for all patients. Using genetics and a holistic view of individual genetics, lifestyle, and environment on a case-by-case basis, doctors are better able to not only predict accurate prevention strategies, but also suggest more effective treatment options.

We’ve come leaps and bounds from where we were in terms of our understanding of DNA 150 years ago. But still, there is much to learn. And with the potential that a deeper understanding of DNA will improve human health and quality of life across our world, no doubt, the research will continue. A full understanding of DNA of and between all living things could one day contribute to solving problems like world hunger, disease prevention, and fighting climate change. The potential truly is unlimited, and to say the least, extremely exciting.

How To Do More With Your DNA

Until recently, individuals were sources of samples in the traditional research model. Today, the gap between research and individual is closing and the community is coming together to contribute health data to support research at scale, advance science, and accelerate medical discoveries at LunaDNATM.

There are so many treatments and cures to diseases that are close to being discovered, and your unique DNA data can help revolutionize the future of medicine.

If you’d like to help researchers better understand you, your family, and your family health history, take the LunaDNA family health history survey or share your DNA data fileThe more people who come together to contribute health data for the greater good, the quicker and more efficient research will scale, and improve the quality of life for us all.  

Click here to get started.