Polycystic ovary syndrome (PCOS) affects approximately 1 in 10 people with ovaries of reproductive age. Even with this condition's high prevalence, we don't have a definitive answer for what causes it.
Research suggests PCOS is caused by a combination of genetics and external environmental factors. Still, explains Dr. Sharon Briggs, PhD, Modern Fertility's head of clinical product and research, we "don't know the exact combination of lifestyle factors, genetics, and unknown risk factors that lead to PCOS." Recent research has been focused on the genetic part of the equation.
In this article, we’re looking at the research around PCOS and genetics — and talking about what it could mean for diagnosis and treatment.
- Polycystic ovary syndrome (PCOS) is a hormonal condition that affects 1 in 10 people with ovaries of reproductive age.
- While we don't definitively know what causes PCOS, there's evidence that PCOS is partly inherited — and partly due to environmental factors.
- Some research has uncovered a link between PCOS and genetics: Certain genetic variants may indicate a higher chance of developing PCOS.
- PCOS is manageable with interventions like lifestyle changes and/or medications — and early detection, talking to your healthcare provider, and understanding your known family history with the condition can make a difference in your experience of it.
What is PCOS?
Polycystic ovary syndrome (PCOS) is a hormonal condition marked by:
- Irregular or absent ovulation
- "Polycystic" ovaries (many underdeveloped ovarian follicles, which aren't the same thing as ovarian cysts)
- High androgen levels ("male" sex hormones like testosterone)
- Other symptoms like excessive hair growth (hirsutism), weight gain, and issues with fertility
Due to the fact that irregular ovulation is a frequent hallmark of PCOS, PCOS is one of the most common causes of infertility. "Regular" ovulation means a mature egg is released from an ovary on a predictable and repeating schedule (typically every 21-35 days). Since some people with PCOS have hyperandrogenism (high androgen levels) and don't produce enough of the hormones that trigger ovulation, this can lead to multiple immature follicles on the ovaries (the fluid-filled sacs that house and develop eggs). But medications like clomiphene (for inducing ovulation) and metformin (for higher blood sugar levels), and even changes in nutrition and exercise can help manage symptoms when you're trying to get pregnant.
It's also common for people with PCOS to have metabolic syndrome — defined by the Mayo Clinic as a “cluster of conditions that occur together,” leading to an increased risk of type 2 diabetes, heart disease, and stroke — and higher body-fat percentages.
What causes PCOS?
The short answer is, we really don’t know the full etiology (cause in medical-speak) of PCOS — but data has shown it’s partially genetic and partially due to environmental factors.
Why don't we know more about what causes PCOS? PCOS is a complex condition with multiple factors and symptoms that often overlap with other issues. Our lack of knowledge here is less about a gap in research efforts and more about that complexity. "It's going to take a ton of work to try to unravel everything," says Dr. Briggs.
In the meantime, keep reading for what do know about PCOS and one of those factors: genetics.
Is PCOS genetic? Here's what the research says
There's an ever-growing body of evidence that demonstrates that a risk of developing PCOS can be passed on from a parent to a biological child. Here's what it tells us so far:
1. PCOS has a heritable component.
2. Researchers have identified specific loci that are associated with PCOS.
The biggest study to date (a genome-wide meta-analysis) among people of European ancestry identified 14 different loci, which are fixed positions on a chromosome where a variant is located, that increase the risk of PCOS. 11 out of the 14 variants they observed replicated older findings and three were new associations.
That said, researchers generally agree (here and here) that there's good evidence for a link between 19 loci and an increased risk of PCOS. It's worth noting that some of this research also incorporated people from the ancestries excluded from the study mentioned above.
But this research only represents part of the equation: "We can currently only explain about 10% of the total genetic heritability based on our current knowledge of genetics and PCOS," explains Dr. Briggs. That means that most of the genetic component is still unknown. Over time, as we learn more about PCOS and its potential biomarkers, we'll get closer to understanding the link between genetics and PCOS — and, importantly, how we can better treat the condition.
How does knowing the cause of PCOS help us treat it better?
Understanding how genes and other factors may play roles in PCOS can help us seek out diagnoses and start treatment earlier. If we know we want to get pregnant in the future, early diagnosis and treatment can help us get ahead of conception challenges caused by menstrual cycle "abnormalities".
Knowing the cause of PCOS may also help people make proactive decisions about how they eat and exercise — potentially making it less likely that issues like insulin resistance and high insulin levels may come up. We may even be able to identify the people who could benefit the most from lifestyle changes, whether that's in terms of better managing the symptoms or decreasing the likelihood of diagnosis.
There's also the possibility that precision medicine, a type of treatment that's highly personalized to each individual and takes genetic makeup into account, could be an option for PCOS patients. Precision medicine has already shown a lot of promise in improving the experiences of people with diabetes, so getting the full picture of genetics and PCOS might enable us to do the same for people impacted by the condition.
Ultimately, the more we talk about PCOS and understand how and why it happens, the more we can destigmatize the condition and its associated symptoms.
The bottom line
It might take decades of research before we know the exact cause of PCOS, but knowing whether or not it runs in your family can help you get a diagnosis and start treatment earlier. If you have a familial history of PCOS and have concerns, don’t be afraid to speak with your healthcare provider.
Most importantly, remember that you’re not alone if you're diagnosed with PCOS. Join the dedicated PCOS channel in the online Modern Community to connect with other people with ovaries who also are managing the condition.
This article was reviewed by Dr. Sharon Briggs, PhD, Modern Fertility's head of clinical product development.