Patients with idiopathic hypogonadotropic hypogonadism have normal gonadotropin-releasing hormone gene structure

Study Objective: To determine if the exons encoding the structural protein for gonadotropin-releasing hormone (GnRH) are present in patients with idiopathic hypogonadotropic hypogonadism (IHH), and whether individual exons possess smaller mutations not detected previously. Design: Study of patients with IHH by DNA analysis using polymerase chain reaction (PCR) and DNA sequencing. Setting: Laboratories of the Department of Obstetrics and Gynecology, Department of Oral Biology, Medical College of Georgia. Participants: Fifteen well-characterized patients (13 females and 2 males) presenting with delayed puberty due to IHH and two fertile controls. Interventions: DNA extraction from all individuals for the performance of PCR and DNA sequencing for exon II, the coding region for the GnRH decapeptide. Main Outcome Measures: For PCR analysis, fragment sizes were evaluated on agarose gels stained with ethidium bromide in the presence of a molecular weight marker. Specific nucleotide sequences were determined from radiographs of DNA sequencing gels. Results: Each of the fragments containing exons II-IV of the GnRH gene were present and of normal size in all patients with IHH and controls. Exon II and splice junction sequences were normal in four females with IHH. Conclusions: PCR of individual exons encoding the structural gene for GnRH is normal in 15 patients with IHH. DNA sequencing of exon II in four women with IHH is normal. PCR analysis and preliminary DNA sequencing fail to demonstrate causative mutations in the GnRH gene in our patients with IHH, which contributes additional information not provided by Southern analysis and previous studies.