The steroidogenic factor 1 (SF1) protein, encoded by the NR5A1 gene, plays a central role in gonadal development and steroidogenesis. Mutations in NR5A1 were first described in patients with primary adrenal insufficiency and 46,XY disorders of sexual development and later also in men with hypospadias, bilateral anorchia and micropenis and women with primary ovarian insufficiency. Recently, heterozygous missense mutations were found in 4% of infertile men with unexplained reduced sperm counts living in France, but all mutation carriers were of non-Caucasian ancestry. Therefore, we performed a comprehensive NR5A1 sequence analysis in 488 well-characterised predominantly Caucasian patients with azoo-or severe oligozoospermia. Two-hundred-thirty-seven men with normal semen parameters were sequenced as controls. In addition to several synonymous variants of unclear pathogenicity, three heterozygous missense mutations predicted to be damaging to SF1 protein function were identified. The andrological phenotype in infertile but otherwise healthy mutation carriers seems variable. In conclusion, mutations altering SF1 protein function and causing spermatogenic failure are also found in men of German origin, but the prevalence seems markedly lower than in other populations.

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Mayer-Rokitansky-Küster-Hauser syndrome (MRKHS) is a well-known malformation pattern of the Müllerian ducts (MDs) characterized by congenital absence of the uterus and vagina. To date, most cases remain unexplained at molecular level. As female Wnt9b-/- mice show a MRKHS-like phenotype, WNT9B has emerged as a promising candidate gene for this disease. We performed retrospective sequence analyses of WNT9B in 226 female patients with disorders of the MDs, including 109 patients with MRKHS, as well as in 135 controls. One nonsense mutation and five likely pathogenic missense mutations were detected in WNT9B. Five of these mutations were found in cases with MRKHS accounting for 4.6% of the patients with this phenotype. No pathogenic mutations were detected in the control group (p = 0.017). Interestingly, all of the MRKHS patients with a WNT9B mutation were classified as MRKHS type 1, representing 8.5% of the cases from this subgroup. In previous studies, two of the patients with a WNT9B mutation were found to carry either an additional deletion of LHX1 or a missense mutation in TBX6. We conclude that mutations in WNT9B were frequently associated with MRKHS in our cohort and some cases may be explained by a digenic disease model.

Fusion anomalies of the Müllerian ducts are associated with an increased risk for miscarriage and premature labor. In most cases polygenic-multifactorial inheritance can be assumed but autosomal-dominant inheritance with reduced penetrance and variable manifestation should be considered. We performed array-comparative genomic hybridization (CGH) analysis in a cohort of 103 patients with Müllerian fusion anomalies. In 8 patients we detected microdeletions and microduplications in chromosomal regions 17q12, 22q11.21, 9q33.1, 3q26.11 and 7q31.1. The rearrangement in 17q12 including LHX1 and HNF1β as well as in 22q11.21 have already been observed in MRKHS (Mayer-Rokitansky-Küster-Hauser syndrome). In summary, we (1) detected causative micro-rearrangements in patients with Müllerian fusion anomalies, (2) show that Müllerian fusion anomalies and MRKHS may have a common etiology, and (3) identified new candidate genes for Müllerian fusion anomalies.