S680N substitution of the follicle-stimulating hormone receptor is a common polymorphism not associated with spontaneous human twinning.

OBJECTIVE: To determine the influence of the A307/S680 and T307/N680 isoforms of the follicle-stimulating hormone receptor (FSHR) gene on the incidence of spontaneous human twinning. DESIGN: Case-control study. SETTING: Departments of Obstetrics and Gynecology and of Clinical Chemistry-Grosshadern, University Hospital Munich, Germany. PATIENT(S): Fifty-four mothers with dichorionic twin pregnancies and 92 singleton mothers as controls, who had conceived without assisted reproduction. INTERVENTION(S): Exon 10 of the FSHR gene was screened for the G2105A/S680N mutation. MAIN OUTCOME MEASURE(S): Amplification of genomic DNA by the polymerase chain reaction followed by restriction fragment length polymorphism analysis. RESULT(S): Allele frequencies for the G2105A/ S680N substitution of the FSHR in twin mothers were not different from those of controls (genotype (isoform) [twins vs. controls]: G/G (S/S) [24.1% vs. 22.3%]; A/G (N/S) [57.4% vs. 55.4%]; A/A (N/N) [18.5% vs. 22.3%]). Subgroup analysis of women with three or more successful pregnancies gave a similar result (G/G (S/S) [17.7% vs. 13.7%]; A/G (N/S) [64.7% vs. 63.6%]; A/A (N/N) [17.6% vs. 22.7%]). There was no correlation between FSHR isoform and twinning. CONCLUSION(S): The S680N substitution of the follicle-stimulating hormone receptor is a common polymorphism not associated with spontaneous human twinning.