X chromosome and ovarian failure.

Genes for reproduction are enriched on the sex chromosomes and they may be involved in the many forms of X- or Y-linked infertility. Here we review the X-linked disorders of ovulation and we show that despite the relatively frequent observation of X chromosome rearrangements in women with ovarian dysgenesis or ovarian failure, the search for X-linked genes has not yet been very fruitful: only two genes have been demonstrated definitively, BMP15 and FMR1. However, the size of the rearrangements and the characteristics of some of the genes suggest that many of the X-linked genes only rarely may be causative and more frequently they may represent risk factors for premature ovarian failure (POF) and will have to be identified by specific approaches. Moreover, recent data seem to suggest a structural and novel role for the X chromosome in some of the POF rearrangements, and also that X-linked POF is not always dependent from the presence of X-linked genes.