The N680S variant in the follicle-stimulating hormone receptor gene identifies hyperresponders to controlled ovarian stimulation.

OBJECTIVE: To study if the follicle-stimulating hormone receptor (FSHR) variant asparagine/serine in amino acid 680 (N680S) can predict hypersensitivity to gonadotropins in women undergoing assisted reproduction. PATIENTS AND METHODS: In this retrospective study, 586 women undergoing their first in-vitro fertilisation treatment were enroled, and their FSHR N680S genetic variant was analysed. The main outcome measures were number of retrieved oocytes and any grade of ovarian hyperstimulation syndrome (OHSS). Experimental studies were performed on FSHR variants transfected into eukaryotic cells treated with 1-90 IU recombinant follicle-stimulating hormone. The receptors' ability to induce a second messenger 3',5'-cyclic AMP was measured. RESULTS: The proportion of women who developed OHSS was 6% (n=36). None of the women who developed this condition had the homozygous serine variant. The N680S polymorphism in the FSHR was associated with the condition, Ptrend (genotype)=0.004 and Pallelic (alleles)=0.04. Mean oocyte number was 11±6 in women without OHSS and 16±8 in women who developed OHSS (P=0.001), despite exposure to lower total hormonal dose in the latter group. The odds ratio for developing OHSS in carriers of the asparagine allele was 1.7 (95% confidence interval: 1.025-2.839, P=0.04). A higher receptor activity in cells expressing asparagine compared with the serine was also evident at all concentrations of recombinant follicle-stimulating hormone used (P<0.05 for all). CONCLUSION: This study confirms previous findings regarding higher hormonal sensitivity in carriers of asparagine in the N680S position. These women are at higher risk for OHSS during in-vitro fertilisation. Genetic testing could identify those at highest risk to develop this adverse effect.

Genotyping common FSHR polymorphisms based on competitive amplification of differentially melting amplicons (CADMA).

PURPOSE: To provide an improved platform for simple, reliable, and cost-effective genotyping. BACKGROUND: Modern fertility treatments are becoming increasingly individualized in an attempt to optimise the follicular response and reproductive outcome, following controlled ovarian stimulation. As the field of pharmacogenetics evolve, genetic biomarkers such as polymorphisms of the follicle stimulating hormone receptor (FSHR) may be included as a predictive tool for individualized fertility treatment. However, the currently available genotyping methods are expensive, time-consuming or have a limited analytical sensitivity. Here, we present a novel version of "competitive amplification of differentially melting amplicons" (CADMA), providing an improved platform for simple, reliable, and cost-effective genotyping. METHODS: Two CADMA based assays were designed for the two common polymorphisms of the FSHR gene: rs6165 (c.919A > G, p. Thr307Ala, FSHR 307) and rs6166 (c.2039A > G, p. Asn680Ser, FSHR 680). To evaluate the reliability of the new CADMA-based assays, the genotyping results were compared with two conventional PCR based genotyping methods; allele-specific PCR (AS-PCR) and Sanger sequencing. RESULTS: The genotype frequencies for both polymorphisms were 35 % (TT), 42 % (CT), and 23 % (CC), respectively. A 100 % accordance was observed between the CADMA-based genotyping results and sequencing results, whereas 5 discrepancies were observed between the AS-PCR results and the CADMA-based genotyping results. Comparing the CADMA-based assays to (AS-PCR) and Sanger sequencing, the CADMA based assays showed an improved analytical sensitivity and a wider applicability. CONCLUSIONS: The new assays provide a reliable, fast and user-friendly genotyping method facilitating a wider implication in clinical practise.

Association between follicle-stimulating hormone receptor polymorphisms and reproductive parameters in young men from the general population.

OBJECTIVE: Follicle-stimulating hormone (FSH) regulates gametogenesis through binding to its receptor (FSHR). In women, the Thr307Ala and Asn680Ser polymorphisms in the FSHR gene affect reproductive function, but it is not clear whether they have any impact on spermatogenesis and have mainly been investigated in infertile men of varying ages. The aim of the present study was therefore to examine whether these genetic variants of the FSHR influence reproductive parameters in men from the general population. METHODS: Men aged 17-20 years (n=313) were genotyped. All men provided a semen sample and a blood sample for hormonal measurements and DNA extraction. They underwent a medical examination and analyses of possible associations between Thr307Ala and Asn680Ser polymorphisms and hormonal and sperm parameters were subsequently carried out. RESULTS: Men homozygous for Thr307/Asn680 had a lower mean serum FSH concentration (3.07 vs. 3.65 IU/l, P=0.009), and higher mean serum estradiol (94.0 vs. 86.1 pmol/l, P=0.001), sex hormone-binding globulin (33.6 vs. 31.3 nmol/l, P<0.0001), and total testosterone (19.1 vs.17.9 nmol/l, P<0.0001) concentrations compared with men with other genotypes. In addition, sperm concentrations (71.9 × 10 vs. 70.8 × 10/ml, P=0.040) and the total sperm counts were higher (212 × 10 vs. 206 × 10, P<0.0001) and their testes volumes were larger (left: 11.5 vs. 11.0 ml, P<0.0001; right: 12.4 vs. 11.6 ml, P=0.002). CONCLUSION: As in women, the results from the present study indicate that variants of the FSHR influence reproductive parameters in men.