Han Chinese polycystic ovary syndrome risk variants in women of European ancestry: relationship to FSH levels and glucose tolerance
Saxena, R., Georgopoulos, N.A., Braaten, T.J. et al.
Are PCOS risk variants identified in women of Han Chinese ethnicity also associated with risk of PCOS or the phenotypic features of PCOS in European women?
One variant, rs2268361-T, in the intron of FSHR was associated with PCOS and lower FSH levels, while another variant rs705702-G near the RAB5B and SUOX genes was associated with insulin and glucose levels after oral glucose testing in women with PCOS of European ethnicity.
WHAT IS KNOWN ALREADY
Three of the eleven variants associated with PCOS in the Han Chinese genome-wide association studies were also associated with PCOS in at least one European population when corrected for multiple testing (DENND1A, THADA and YAP1). However, additional replication is needed to establish the importance of these variants in European women and to determine the relationship to PCOS phenotypic traits.
STUDY DESIGN, SIZE, DURATION
The study was a case–control examination in a discovery cohort of women with PCOS (n = 485) and controls (n = 407) from Boston (Boston 1). Replication was performed in women from Greece (cases n = 884 and controls n = 311) and an additional cohort from Boston (Boston electronic medical record (EMR); n = 350 cases and n = 1258 controls).
PARTICIPANTS/MATERIALS, SETTINGS, METHODS
Women had PCOS defined by the National Institutes of Health criteria in Boston 1 and Greece (n = 783), with additional subjects fulfilling the Rotterdam criteria (hyperandrogenism, polycystic ovary morphology and regular menses) in Greece (n = 101). Controls in Boston and Greece had regular menstrual cycles and no hyperandrogenism. The second cohort from Boston was defined using the EMR and natural language processing. Allele frequencies for variants associated with PCOS in Han Chinese women were examined in PCOS cases and controls, along with the relationship to quantitative traits.
MAIN RESULTS AND THE ROLE OF CHANCE
A variant rs2268361-T in an intron of FSHR was associated with PCOS (0.84 [0.76–0.93], OR [95% CI]; P = 0.002). The rs2268361-T was associated with lower FSH levels (−0.15 ± 0.05; P = 0.0029). A variant rs705702-G near RAB5B and SUOX was associated with insulin (−0.16 ± 0.05, P = 0.0029) and glucose levels (−0.20 ± 0.05, P = 0.0002) 120 min after an oral glucose test.
LIMITATIONS, REASONS FOR CAUTION
The study was large and contained replication cohorts, but was limited by a small number of controls in the Greek cohort and a small number of cases in the second Boston cohort. The second Boston group was identified using electronic medical record review, but was validated for the cardinal features of PCOS.
WIDER IMPLICATIONS OF THE FINDINGS
This study demonstrates a cross-ethnic PCOS risk locus in FSHR in women of European ancestry with PCOS. The variant may influence FSH receptor responsiveness as suggested by the associated change in FSH levels. The relationship between a variant near RAB5B and SUOX and glucose stimulated insulin and glucose levels suggests an influence of one of these genes on glucose tolerance, but the absence of a relationship with PCOS points to potential differences in the international PCOS patient populations.
Saxena, R., Georgopoulos, N.A., Braaten, T.J. et al. "Han Chinese polycystic ovary syndrome risk variants in women of European ancestry: relationship to FSH levels and glucose tolerance" Human Reproduction (2015): 1,454–9