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 isofor ms of the follicle-stimulating hormone receptor (FSHR) gene on the incidenc e 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 sin gleton 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 cha in 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 (isofo rm) [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 thre e 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 r eceptor is a common polymorphism not associated with spontaneous human twin ning.