Polycystic ovary syndrome (PCOS), one of the most common endocrine disorders of reproductive age women, is associated with an increased risk of type 2 diabetes mellitus. Defects in both insulin action and insulin secretion contribute to this predisposition to diabetes, but the extent to which these defects are heritable among PCOS families has not been examined.
In the present study we used the frequently sampled iv glucose tolerance test to quantitate insulin secretion (AIRg), insulin action (Si), and their product (AIRg × Si) among women with PCOS (n= 33) and their nondiabetic first degree relatives (n = 48). We then quantitated the heritability of these measures from familial correlations estimated within a genetic model.
Familial (spousal, ρMF; parent-offspring, ρPO; and sibling, ρSS) correlations were derived for log-transformed body mass index (BMI) as well as for AIRg, Si, and AIRg × Si, the latter three of which were adjusted for BMI. There was no evidence of significant heritability for either lnBMI or lnSi in these families. In contrast, the sibling correlation (ρSS = 0.74) for lnAIRg was highly significant (χ2 = 7.65; 1 df; P= 0.006). In addition, the parameter quantitating insulin secretion in relation to insulin sensitivity [i.e. ln(AIRg × Si)] was significant among siblings (ρSS = 0.74;χ 2 = 4.32; 1 df; P = 0.04).
In summary, the results of the present study indicate that there is an heritable component to β-cell dysfunction in families of women with PCOS. We conclude that heritability of β-cell dysfunction is likely to be a significant factor in the predisposition to diabetes in PCOS.
Glucose Intolerance in Obese Adolescents with Polycystic Ovary Syndrome: Roles of Insulin Resistance and β-Cell Dysfunction and Risk of Cardiovascular Disease1
