Scientists Discover Two Subtypes of PCOS

There are two distinct types of polycystic ovary syndrome (PCOS)—the little-understood condition that is a leading cause of infertility in women—according to a study.

The authors of the paper published in the journal PLOS Medicine believe patients either have "reproductive" or "metabolic" PCOS. These types were in turn linked with particular regions in the participants' genetic make-up.

PCOS, which is thought to affect 15 percent of women of reproductive age, is a leading cause of infertility. It is also associated with type 2 diabetes, as those with the condition can be resistant to insulin. According to the U.S Centers for Disease Control and Prevention, more than half of women with PCOS develop type 2 diabetes by age 40.

PCOS patients are more likely to have higher levels of androgens (male hormones which are also present in females) that can prevent eggs from being released from the ovaries, making periods irregular. Acne, as well as excess hair on the face and body but thinning head hair, are also symptoms.

To investigate whether there are subtypes of PCOS, the scientists looked at data they had collected for a previous study. The information on the 893 women with PCOS included hormone, glucose and insulin levels, as well as their genetic make-up.

The team used a mathematical technique to group the women according to their similarities, revealing the two subtypes. By comparing the genetic data of the participants, the team were able to pinpoint parts of the genome linked with the different subtypes.

Those in the reproductive subtype were more likely to have higher levels of luteinizing hormone (LH) that acts on the ovaries and triggers ovulation, and a protein called sex hormone binding globulin (SHBG) which regulates how testosterone enters certain tissues. This group was more likely to have a relatively low BMI and insulin levels. In contrast, those in the metabolic category were more likely to have a higher BMI, on average, blood glucose and insulin levels, as well as lower SHBG and LH levels.

To corroborate their findings, the scientists then looked at a separate group of 263 PCOS patients, for whom they didn't have genetic information, and found the same patterns.

Co-author Dr. Andrea Dunaif, chief of the Hilda and J. Lester Gabrilove Division of Endocrinology, Diabetes and Bone Disease at the Mount Sinai Health System, told Newsweek the study is important because the cause of PCOS is unknown, meaning patients are currently diagnosed using controversial and arbitrary criteria based on expert opinion rather than knowledge of disease mechanisms.

As with any research, the study has its limitations. For instance, the team were unable to assess the genetic data on the second group of women. In addition, the study only included people of European ancestry, so more research is needed to see if the same subtypes are found in women of different racial and ethnic backgrounds, Dunaif said.

Although PCOS is common and is linked to major health problems, little progress has been made in diagnosing and treating the condition since the 1990s, Dunaif said. It can often take too long for people to be diagnosed, and doctors, especially primary care providers, are poorly informed about the condition. There is also a lack of funding for research.

"Women with PCOS are appallingly underserved by the medical community," Dunaif said.

Dunaif hopes the findings will help uncover the causes of PCOS and find ways to develop new treatments, including personalized medicine, and to predict cases.

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A stock image shows the female reproductive organs alongside a stethoscope. Getty