A common polymorphic allele of the LH beta-subunit gene is associated with higher exogenous FSH consumption during controlled ovarian stimulation for assisted reproductive technology

BACKGROUND: V-betaLH is a common genetic variant of LH caused by two polymorphic base changes in the beta subunit gene, altering the amino acid sequence (Trp8Arg and Ile15Thr). In a previous-preliminary trial performed in women undergoing IVF, it was demonstrated that carriers of v-betaLH show sub-optimal ovarian response to a standard long GnRH-agonist down -regulation protocol when stimulated with pure recombinant FSH (r-hFSH). The aim of this study was to confirm the hypothesis that women with v-betaLH display hypo-sensitivity to exogenous FSH in a larger IVF population and to explore the frequency of this variant in a Danish female population. METHODS: In the present study, the effect of v-betaLH was retrospectively investigated in a larger series of women undergoing controlled ovarian stimulation (COS) and, for the first time, in a Danish IVF population. A total of 220 normogonadotrophic women following a long GnRH-agonist down-regulation protocol received an individualized dose of r-hFSH (100 IU and 375 IU s.c. daily) according to antral follicle count, baseline FSH, body mass index and age. The LH genotype was assessed in all patients by immunofluorometric assay. RESULTS: V-betaLH was present in 11% of patients, whereas the allelic frequency was 12%. The study population was divided into two groups according to their LH genotype. Group A consisted of 196 wt/wt women. Group B included 24 individuals with v-betaLH (21 heterozygous and 3 homozygous). No statistically significant differences in the mean number of oocytes retrieved, fertilization rate and pregnancy rate per cycle were observed between groups. However, Group B received a significantly higher cumulative-dose of r-hFSH than Group A (2435.86 +/− 932.8 IU versus 1959.8 +/− 736.45 p = 0.048). When one-way ANOVA in a within design was applied, the LH genotype had a statistically significant effect (p < 0.01) on the cumulative dose of r-hFSH, showing a progressive increase from wt/wt (1959.8 +/− 736.45 IU) to v-betaLH hetero- (2267.5 +/− 824.3) and homozygotic women (3558.3 +/− 970.9). CONCLUSIONS: These results confirm that carriers exhibit hypo-sensitivity to exogenous FSH during COS, documenting that the frequency of v-betaLH in Denmark is similar to a number of European countries.