At baseline, there was no detectable difference in copy number (copies/μL) of methylated (p = 0.74) or unmethylated INS cfDNA (p = 0.34) between PCOS and Control groups.
We have observed evidence of association with two independent TCF7L2 loci in a PCOS cohort: 1) association between the proinsulin:insulin molar ratio and the T2D locus; and 2) association with reproductive PCOS phenotype and a novel locus.
The results of previous research about the association of the VNTR polymorphism in 5-prime flanking region of the insulin (INS) gene with PCOS have been inconsistent.
Polymorphism of C/T in the low-density lipoprotein receptor-related protein-5 gene is associated with C-peptide and proinsulin secretion but does not influence insulin sensitivity in either healthy women or women with polycystic ovary syndrome.
We suggest that INS VNTR genotypes are not associated with PCOS in general, but could have a certain influence on the phenotypic spectrum of the syndrome.
A8 was also associated with higher levels of fasting insulin and homeostasis model assessment for insulin resistance in women with PCOS and higher fasting levels of proinsulin and proinsulin/insulin ratio in brothers.
However, obese n-INS and lean h-INSPCOSs showed a similar low GLUT4 expression, whereas obese h-INSPCOSs showed the lowest expression when compared with other groups.
Troglitazone, an insulin-sensitizing thiazolidinedione, represses combined stimulation by LH and insulin of de novo androgen biosynthesis by thecal cells in vitro.
In spite of several differences in anthropometric and biochemical parameters (abdominal fat localization, increased beta-cell function, and lower insulin sensitivity in PCOS women), no effect of INS VNTR polymorphism was found on insulin secretion, insulin action, or any other screened parameter.
PCOS sisters had increased levels of proinsulin (P = 0.04) compared with control women, which suggested pancreatic beta-cell dysfunction in this group of sisters.