Mutation analysis of the inhibin alpha gene in a cohort of Italian women affected by ovarian failure.

BACKGROUND

Premature ovarian failure (POF) is a secondary hypergonadotrophic amenorrhoea affecting 1-3% of females, whose aetiology is almost unknown. However, inhibin alpha gene (INHalpha) has recently been indicated as candidate in POF pathogenesis.

METHODS

We analysed patients affected by POF (n = 157) for the missense mutation (769G-->A transition) in the exon 2 of the INHalpha gene. The same analysis was carried out on early menopause (EM) (n = 36) and primary amenorrhoea (n = 12) patients.

RESULTS

The incidence of the mutation was significantly more frequent within both POF (7/157, 4.5%) (Fisher's exact test, P = 0.030) and primary amenorrhoea (3/12, 25%) (Fisher's exact test, P < 0.001) patients, compared with the control population of women (0/100), who experienced physiological menopause. No mutation was found in EM patients. Furthermore, the likelihood of finding the mutation was statistically significant in familial (5/65; 7.7%) (Fisher's exact test, P < 0.01) but not in sporadic (2/92; 2.2%) (Fisher's exact test, P = not significant) POF, compared with the control group. The analysis of pedigrees showing the inheritance of the 769G-->A mutation and POF strengthens the concept of the disease heterogeneity, since the POF phenotype was not always associated with the mutation. Moreover, a higher prevalence of the C allele of a single nucleotide polymorphism (129C-->T), located in the 5'-UTR of the INHalpha gene, was observed in POF patients (80.3%) than in the control group (66.7%) (Fisher's exact test, P = 0.014).

CONCLUSION

These data strengthen the concept of the INHalpha gene as a candidate for ovarian failure.