Mutations in gonadotropin-releasing hormone signaling pathway in two nIHH patients with successful pregnancy outcomes

Abstract

Background: Anomalous levels of gonadotropin-releasing hormone (GnRH) secretion result in a variety of reproductive phenotypes associated with infertility or subfertility. The normosmic isolated hypogonadotropic hypogonadism (nIHH) is due to a failure of either GnRH pulsatile secretion in hypothalamus or its reception in pituitary. The spectrum of nIHH-associated alterations continues to expand, especially when additional ethnic populations are investigated. The aim of this study was to uncover genetic causes for nIHH in patients of Russian origin. Methods: For two nIHH patients referred to infertility clinic, both exons and promoter sequences of 6 GnRH signaling genes were sequenced. Results: Patient 1 was a compound heterozygote for mutations in GnRH and its receptor encoding genes, while in Patient 2 GnRHR mutations were found in homozygous state. In both patients, the coding frame of GnRHR gene harbored missense-mutation Arg139His previously described as founder mutation in Polish and Brazilan patients. IVF/ET treatments were successful, with phenotypically healthy offsprings delivered. Conclusion: Polish founder mutation Arg139His in GnRHR was found in two nIHH patients originating from Western region of Russia. Common variant of GnRH-encoding gene, Trp16Ser, could possibly contribute to reproductive phenotypes in patients with heterozygous mutations of other GnRH signaling pathway genes.