Gene Diagnosis Of Idiopathic Hypogonadotropic Hypogonadism And Initial Function Study Of Pathogenic Mutation

Background:Isolated hypogonadotropic hypogonadism (IHH) is characterized by delayed or absent sexual development associated with inappropriately low gonadotropin and sex steroid levels in the absence of anatomical or functional abnormalities of the hypothalamic-pituitary-gonadal axis. Kallmann syndrome (KS) is a congenital defect characterized by the presence of hypogonadotropic hypogonadism and anosmia/hyposmia.KS is accounted for 60%of IHH. It is also occasionally associated with additional features such as mirror movements, cleft palate and renal agenesis/dysgenesis.KS is a genetically heterogeneous disease, which affects 1:8000 males and approximately five times less females.It may be caused by mutations in several genes. There include KAL1 on Xp22.3 for the X-linked form, FGFR1 for the autosomal dominant form of the disease,and PROKR2 or PROK2 were also found in patients with KS-most were heterozygous But mutations in these genes account for barely 30%of all KS cases.Objective:We screened 18 patients diagnosed with IHH. Final we detect the underlying genetic defect in 18 patients with IHH and perform the gene function research to the patients of inspecting gene mutation. And provide the theoretical basis for the accurate diagnosis and even prenatal diagnosis of IHH.Methods:Mutation analysis of KAL1, FGFR1, FGF8, PROK2 and PROKR2 were performed with PCR and DNA Sequencing.finally functional analysis of the HA-tagged Prokr2 mutants.Results:(1) We don't found any mutations in the gene KAL1, FGFR1, FGF8, PROK2 (2) three mutations are been detected:991 G> A and 533 G > C,151 G> A. The 991 G> A transition in codons 331 is discovered in two patients,which resulted in the replacement of valine by methionine acid respectively, The 533 G> C transition in codons 178 is found in one patient, which resulted in the replacement of tryptophane by serine acid respectively, The 151 G> A transition in codons 51 is detected in three patients, which resulted in the replacement of alanine by threonine acid respectively.The last A51T is a novel mutation. (3) 151 G> A missense mutations impair intracellular Ca2+increase evoked by PROK2Conclusions:(1) We found three heterozygous mutations:c.991 G> A, c.533 G> C, c.151 G>A which cause the disease of KS.We identified a novel morbigenous mutation of PROKR2 in 3 Chinese patients. This expanded the mutation spectrum of PROKR2 and provided data elucidating the diverse and variable effects of PROKR2 mutations.(2) PROKR2 missense mutations of c.151 G> A impair intracellular Ca2+ increase evoked by PROK2,which is the reason of suffering from KS.