Chronic Fatigue Syndrome Genetics

Chronic fatigue syndrome can run in families, which has led researchers to ask, “Is chronic fatigue syndrome genetic?” A lot of people with this disease also ask that question, wondering whether they’ll pass it on to a child or whether they have it because one of their parents did.

Chronic fatigue syndrome, more recently named myalgic encephalomyelitis or ME/CFS, involves dozens of possible symptoms, including constant debilitating fatigue, disturbed sleep, cognitive dysfunction (“brain fog”), and—its hallmark symptom—an extreme reaction to exertion called post-exertional malaise.

Researchers have much to still learn about ME/CFS, as it’s a complex disease involving multiple systems in the body. However, one thing many of them agree on is that ME/CFS isn’t an inherited condition, but it does involve a genetic predisposition and abnormalities in certain genes.

Why Genetic Research Matters

ME/CFS is generally classified as an immune disease, and sometimes as a neuroimmune or neuro-endocrine-immune disease, which reflects its multi-system complexity. Given that, some people with this disease wonder why researchers “waste time” looking at genetics.

While ME/CFS isn’t a genetic disorder, genetics has much to teach us about it. Through genetic research, we may gain:

Objective diagnostic markers, which would help doctors identify this hard-to-diagnose condition
Treatments aimed at correcting specific genetic changes due to ME/CFS, which means they’re targeting the disease process and not just alleviating symptoms
Genetic testing that may reveal who’s likely to develop ME/CFS and what treatments are most likely to work
ME/CFS prevention based on genetic testing
Proper identification of subtypes, which most experts believe is critical to understanding and treating the disease

Currently, ME/CFS is a diagnosis of exclusion, meaning doctors diagnose it by ruling out other possible causes of your symptoms.

Treatment Shortcomings

Despite decades of research, people with ME/CFS still have no treatments approved by the U.S. Food and Drug Administration. While several off-label treatment options are available, many people don’t get adequate relief from them.

Familial Patterns

Research suggests that ME/CFS does run in families. Having a close relative with the disease may increase your risk of developing it by 13%, according to one study.

In a study looking at first, second, and third-degree relatives of someone with ME/CFS, data suggest that the risk is greater even for more distant relatives.

It’s unlikely that there’s one “ME/CFS gene,” though. Studies show that the pattern of cases within families doesn’t follow a predictable pattern like some diseases do. This leads experts to believe it’s more likely that many genetic variables are involved.

Type of Relative	Who That Is	Increase in Risk
1st degree	Parent, sibling, child	2.7 times
2nd degree	Grandparent/child, aunt/uncle, niece/nephew, half-sibling	2.34 times
3rd degree	First cousin, great-grandparent/child	1.93 times

Source: Albright, et al.

Genetic Predisposition

While you may have inherited a genetic predisposition, or susceptibility, to ME/CFS, that doesn’t mean you’ll someday develop it. A genetic susceptibility is different from a hereditary disease:

In a true genetic disease: If you inherit the gene, you either have or will eventually have the disease.
With a genetic predisposition: You inherit genes that make it possible or likely for you to develop the condition under the right circumstances. If those circumstances never come to pass, you probably won’t develop ME/CFS.

Research suggests the inherited portion of ME/CFS is only about 10% of the overall cause. This means that it takes a genetic predisposition combined with other factors to trigger the disease.

Examples

An example of something that may combine with genetic predisposition to trigger ME/CFS, according to 2018 research, is numerous infections of the digestive tract or airways. In response to the infections, only genetically susceptible people appear to develop what are called “autoreactive B cells.”

B cells are a part of the immune system that creates antibodies (proteins that are supposed to fight off infection). When B cells are autoreactive, it means it produces proteins to attack the other disease-fighting cells from your immune system.

Over time, some of these B cells can create autoantibodies (proteins that attack healthy tissues as though they were a dangerous invader, like a virus.) These autoantibodies target key enzymes that deal with energy metabolism, which is what researchers believe leads to the hallmark symptom of ME/CFS: post-exertional malaise.

Infection with the Epstein-Barr virus (EBV, which causes mononucleosis) is also believed to start a reaction in susceptible people that leads to abnormal activity from B cells and T cells (another type of immune cell) and triggers ME/CFS.

What It Means to Have a Genetic Predisposition

Associated Genes

Researchers have identified a number of genes that may be involved in ME/CFS. One study found activity changes in nearly 1,200 sites that correspond to more than 800 genes. Various studies have found changes in genes that deal with:

Integrity of the blood-brain barrier
Neuroplasticity (ability of the brain to make new connections in response to learning)
Immune-system activation not related to infection
Regulation of the immune system
Metabolic function, including the processing of sugars and fats
Activity of hormones (naturally produced glucocorticoids, estrogen, androgens)
Receptors of the neurotransmitter glutamate
Sensitivity to glucocorticoids
Stress-response system regulation
Enzymes that affect DNA expression
T cell function

One study found more than 100 changes to genes associated with T-cells alone. Some immune-system changes may even be an underlying mechanism of ME/CFS.

Other Triggering Factors

So far, researchers don’t know the exact role of most causal and risk factors in ME/CFS, although, as demonstrated by the research cited above, they appear to be gaining important ground.

Factors beyond genetics that are believed to contribute to the development of the disease include:

Infection, especially viral, such as with EBV
Flu-like illness
Immune system abnormalities
Stressful conditions
Central nervous system abnormalities
Hormonal imbalance
Exposure to toxins

Women are diagnosed with ME/CFS between two and four times more than men. This could be accounted for, at least in part, by hormonal differences and reproductive events such as childbirth, menstruation, and menopause.

Preventing ME/CFS

If you believe you or someone close to you is genetically predisposed to ME/CFS, you may be able to take some steps to make the disease’s onset less likely:

Avoid infectious illnesses (e.g., get vaccinated, avoid sick people, wear a mask, wash hands)
Get prompt treatment for infectious illnesses
Live a generally healthy lifestyle (healthy diet, exercise, not smoking)

A Word From Verywell

ME/CFS is difficult to diagnose and treat. Right now, doctors don’t know enough about ME/CFS to predict who will or won’t develop the disease. They also don’t know how to prevent it.

Genetic research could one day give them objective biomarkers for diagnosis, targeted treatments, genetic testing to see who’s susceptible, and the necessary tools to delay or prevent its onset.