Mutation analysis of the gonadotropin-releasing hormone receptor gene in idiopathic hypogonadotropic hypogonadism

Objective: To determine if GnRH receptor mutations occur in patients with idiopathic hypogonadotropic hypogonadism. Design: Patients and controls were studied by molecular genetic analysis. Setting. A tertiary medical center setting. Patient(s): Twenty-four patients with idiopathic hypogonadotropic hypogonadism and 20 controls. Intervention(s): Deoxyribonucleic acid from all individuals was analyzed by Southern blot analysis and denaturing gradient gel electrophoresis. Genomic DNA was digested with restriction enzymes, and Southern blots and denaturing gradient gel blots were constructed. Blots were hybridized with the GnRH receptor complementary DNA probe. The DNA sequencing was performed on samples from two representative patients. Main Outcome Measure(s): Gonadotropin-releasing hormone receptor gene structure was ascertained by comparing fragments from autoradiographs in patients and controls. Individual nucleotides were ascertained from DNA sequencing gels. Result(s): No GnRH receptor gene deletions or polymorphisms were identified by Southern blot analysis. New restriction-fragment melting polymorphisms using the enzymes DpnII, RsaI, and HaeIII were identified by denaturing gradient gel blots in patients and controls. Conclusion(s): Gonadotropin-releasing hormone receptor gene deletions or rearrangements were not observed in our idiopathic hypogonadotropic hypogonadism patients. Denaturing gradient gel electrophoresis failed to identify single-base differences unique to patients with idiopathic hypogonadotropic hypogonadism, dramatically reducing the likelihood that point mutations of the GnRH receptor gene are present in idiopathic hypogonadotropic hypogonadism.