Combined in vitro and in silico analyses of FGFR1 variants: genotype-phenotype study in idiopathic hypogonadotropic hypogonadism.

Fibroblast growth factor receptor 1 (FGFR1) is an idiopathic hypogonadotropic hypogonadism (IHH)-associated gene, mutated in approximately 10% of the patients with this condition. Through targeted gene sequencing of 153 males with IHH and 100 healthy controls, we identified 10 mutations in FGFR1 from IHH patients with a frequency of 5.9% in the Chinese population of central China. These included nine missense mutations(NM_023110.2, p.Gly687Arg, p.Ala608Asp, p.Gly348Glu, p.Asn296Ser, p.Gly226Asp, p.Arg209Cys, p.Gly97Arg, p.Val71Met, p.Gly70Arg) and a splicing mutation c.1430 + 1G > T. in vitro and in silico analyses of FGFR1 variants were conducted to study the impact of the identified mutations. Our findings indicated that the splicing mutation dramatically affected premRNA processing, causing exon 10 and 6 nucleotides in the 3' end of exon 9 to be completely skipped. Two variants (p.Gly687Arg and p.Ala608Asp) markedly impaired tyrosine kinase activity, while the other variants had limited impact on the mitogen-activated protein kinase (MAPK) signaling pathway. However, the functional impairment of the mutant receptors was not always consistent with the phenotypes, indicating that FGFR1 mutations might cause IHH in conjunction with other mutant genes. In this study, we expanded the knowledge on the mutation spectrum of FGFR1 in IHH patients and explored the genotype-phenotype relationship.