“Do you have a family history of that?” It’s a question that often comes up in health settings, but how much does genetics influence your physical and mental health?
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“Do you have a family history of it?”
It’s a question that often comes up in health settings, but how much does genetics influence your physical and mental health?
“Almost every condition you can think of has some sort of genetic basis, but the genetic basis is variable,” said Dr. Eimear Kenny explains. “For some conditions, you can point to specific genetic factors, and those genetic factors usually explain most of why you have the condition … but that’s really just the tip of the iceberg.”
For other conditions, genetics may be a small part of the puzzle. And it may vary in different contexts.
For example, if you have high cholesterol, it’s usually due to a combination of your genetic predisposition, diet, and other lifestyle factors — but for some, the genetic factor may be stronger.
“For some people, about one in 200 people in the world, their high cholesterol is actually a very large genetic factor,” Kenney told CBS News. “There is a condition called familial hypercholesterolemia, which causes high cholesterol at a very young age for genetic reasons.”
That’s why family history remains one of the “most important things in medicine,” Kenney says, because it can help you and your doctor determine the level of your risks.
To better understand, we explored the most frequently searched questions about the genetic component of several common conditions.
Is diabetes genetic?
If your mother, father, sister or brother has type 2 diabetes, you may have prediabetes — high normal blood sugar levels — and be more likely to develop type 2 diabetes, according to the Centers for Disease Prevention and Control.
Kenny says there are also genetically driven forms of diabetes, such as MODY – maturity-onset diabetes of the young – which affects 1-2% of people with diabetes, but often goes unrecognised.
“It affects a very small minority, but that’s where there’s a strong genetic driver,” Kenny explains.
“For the rest of us, our genetic contribution to diabetes is a small piece of the pie compared to the social determinants of health. But there are many individuals at the high end of that risk, individuals at the low end of that risk, and sometimes individuals at the high end of that risk who have the same risk for those rare genetic drivers.
Even if you have a family history of diabetes, the CDC says you can prevent or delay type 2 diabetes by making lifestyle changes — eating a healthy diet, being physically active and maintaining a healthy weight. This is especially important if you have prediabetes, which can be reversed.
Is Alzheimer’s genetic?
According to the National Institutes of Health, most cases of Alzheimer’s have no genetic cause. Instead, “multiple genes combined with lifestyle and environmental factors” can influence the disease.
“Importantly, people who develop Alzheimer’s do not always have a history of the disease in their families,” notes the NIH’s website. “Still, those who have a parent or sibling diagnosed with the disease are more likely to develop Alzheimer’s than those without that association.”
Less than 5% of Alzheimer’s cases are actually inherited, says neuroscience researcher and neurodegenerative disease expert Dr. Dale Bredesen explains, however, that a set of figures has been identified. For others, there is no apparent link.
“So 95% is sporadic, meaning you can inherit a proclivity for it, but you don’t necessarily get it,” he says. “Just 5% are associated with three different genes,” known as the APP gene, presenilin 1, and presenilin 2. “In those cases, if you inherit that gene, you usually get the disease.”
Within the 95% group, two-thirds have a gene that increases or decreases the risk of Alzheimer’s, says Bredesen.
One known gene that influences Alzheimer’s risk is the apolipoprotein E, or APOE, gene, which comes in different forms, or alleles. Among these alleles, APOE4 is understood to be the most important genetic risk factor.
“The APOE gene is involved in making a protein that helps transport cholesterol and other types of fat in the bloodstream,” the NIH’s website explains. “Problems in this process are thought to contribute to the development of Alzheimer’s.”
Although APOE testing is available, the results cannot fully predict who will or will not develop Alzheimer’s. However, Bredesen still thinks “knowing your status” is useful for assessing your risk and taking steps to protect your health.
“If you have a single copy of APOE4 — which is 75 million Americans — your lifetime risk goes from about 9% to 30%. If you have two copies, which is 7 million Americans, it goes up to about 70%,” he explains.
But he stresses, “It’s important to note that this is only a risk. That doesn’t mean you’ll get it, in fact, there’s a lot you can do to make sure you don’t.
For example, research suggests that maintaining a healthy diet, keeping your mind and body active, and avoiding smoking and excessive alcohol consumption can help improve your chances.
Is bipolar disorder or schizophrenia genetic?
Studies have shown that bipolar disorder, especially the most severe type, has a strong genetic component. Scientists are working to understand the apparent genetic risk factors for schizophrenia.
For mental health and neuro-psychiatric disorders, few people have strong genetic drivers, Kenny says – but these can be more challenging to pin down.
“When we want to ask if your heart is healthy, we have a way of imaging the heart. We have a way to measure the thickness of your arteries. We can measure your heart rate, blood pressure, EKG – we have all these devices,” she says. “But when we want to understand the picture of your mental health, we only have accurate quantitative measures of it. So it’s a little more difficult to understand how genetics influences that, but we’re improving.
Is autism genetic?
Autism is another disorder that falls under the scientific category of “improvements” in understanding specific genetic drivers, Kenney says.
Experts know that genetics, biology, and environment are all important factors, according to the CDC.
“If someone in your family has autism spectrum disorder (ASD), you are more likely to have a child with ASD,” according to the agency’s website. “Older parents, a difficult birth, or infections during pregnancy are all examples of factors that increase the risk of developing ASD.”
Autism is also complicated because it exists on a spectrum, said Dr. Wendy Chung explains.
At the moment, genetic tests for people across the spectrum will give only about 10% of individuals a genetic answer that explains a major factor that causes their autism, she says.
“Most of the people who get that single genetic answer back … are individuals who either have intellectual disabilities, epilepsy, or other major medical problems. Those are the individuals who are more challenging in the sense of co-occurring conditions,” says Chung. Conversely, high-functioning individuals have a harder time finding genetic results through testing.
“That doesn’t mean there aren’t genetic contributors, but based on our current knowledge…we can’t put our finger on them.”
Is ADHD genetic?
According to the Attention Deficit Disorder Association, ADHD can also run in families.
“The genes you inherit from your parents can significantly affect your risk of developing ADHD,” the association notes on its website. “People who have a parent, sibling, or close relative with ADHD are also more likely to develop ADHD.”
In addition to genetics, scientists are studying other causes and risk factors for ADHD, including brain damage and exposure to various environmental factors during pregnancy or early childhood, the CDC says.
Compared to autism, “we’re far behind in identifying (genetic factors) for ADHD,” Chung says. “Thankfully, we have a little better treatment, so it’s not as challenging as autism.”
But for people with co-occurring conditions, it may be easier to identify a genetic factor.
“It’s possible that people with ADHD who develop epilepsy, for example, have an identifiable genetic component,” Chung explains, but more research is needed to better understand the causes of most ADHD.
Why are genetic factors important?
Kenny says understanding how genes play a role in the risk of certain conditions is key to helping with prevention.
A well-known example involves the BRCA1 and BRCA2 genes, where testing for specific mutations can show whether someone is more likely to develop breast cancer and other cancers. But the results still leave patients with many questions about their best course of action.
“About 25% of people with a pathogenic variant in a BRCA1 or BRCA2 gene are more likely than others to develop the associated cancers,” she says, adding that she hopes for better genomic screenings in the future.
“If (physicians) know you’re at high risk, they can adjust your health management … to try to detect the disease before or before symptoms develop and reduce or prevent mortality.”
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