What's Your Phenotype?
A phenotype is a unique set of characteristics based on your genetic makeup and influence of environmental factors. In a position paper published in Fertility and Sterility, the Androgen Excess and PCOS Society Task Force suggest that there at least 10 possible phenotypes of PCOS. The difference in phenotypes explains how the syndrome has so much variation in symptoms. For example, despite the core feature of PCOS being high levels of androgens, not all women with the syndrome have excess hair growth on their body while some women may have full-grown beards. Others have acne and some have none. Some women with PCOS are lean while others are overweight. A small percentage of women may have no symptoms of PCOS whatsoever. The classification of phenotypes also includes ovulation. The most difficult phenotype to treat may be the non-ovulatory hyperandrogenism group.
According to the consensus on women's health, published this year in Fertility and Sterility, "there is considerable ethnic variation in the expression of PCOS, including the prevalence and severity of obesity, metabolic disturbances and their correlates." They explain that geographic location, ethnic origin and even cultural and social practices are contributing factors to the different phenotypes. For example, Asian women are generally shorter, have a lower BMI but central obesity, and a milder hyperandrogenic phenotype. However, South Asians have a higher prevalence of metabolic syndrome. African American and Hispanic women are more obese and have metabolic problems. Women of Middle Eastern descent have more hirsutism.
There is no question that lifestyle contributes to the phenotype expression of PCOS. We know, for example, that weight gain worsens pretty much all aspects of the syndrome and that weight loss improves most aspects. A sedentary lifestyle worsens metabolic parameters and an active lifestyle improves them. Depending on one's phenotype, nutritional supplements may improve PCOS for some but not for others. The difference in phenotypes explains why some women respond better to different ways of eating. For example, one woman may lose weight following a low GI diet but another does better on a reduction in carbohydrates.
PCOS is a hereditary condition. Women who have PCOS have 20% to 40% first-degree female relatives who also have the syndrome. Family members can have different phenotypes of PCOS. My sister has the nonovulatory hyperandrogenism phenotype while I have the ovulatory hyperandrogenism phenotype yet we are only 17 months apart in age.
The progress in PCOS genetics is limited due to varied diagnostic criteria, small study sample sizes and difficulty assigning a phenotype. We do know that further understanding of the genetics of PCOS will help us to determine which diet, medication, nutritional supplement or overall treatment approach is best depending on one's phenotype. If only we had a crystal ball!
Fauser B, Tarlatizis B, Rebar R. Legro R, Balen A, Lobo R. Consensus on women's health aspects of polycystic ovary syndrome (PCOS): the Amsterdam ESHRE/ASRM-Sponsored 3rd PCOS Consensus Workshop Group. Feril Steril. 2012;97:28-97.
Diamanti-Kandarakis E, Christakou C, Marinakis E. Phenotypes and environmental factors: their influence in PCOS. Curr Pharm Des. 2012 Jan 1;18(3):270-82.
Azziz R, Carmina E, Dewailly D, Diamanti-Kandarakis E, Escobar-Morreale HF, Futterweit W, Janssen OE, Legro RS, Norman RJ, Taylor AE, Witchel SF; Task Force on the Phenotype of the Polycystic Ovary Syndrome of The Androgen Excess and PCOS Society. The Androgen Excess and PCOS Society criteria for the polycystic ovary syndrome: the complete task force report. Fertil Steril. 2009 Feb;91(2):456-88.