【作者】 法塞（Aws Khalid Fathi）；

【导师】 罗小平；

【作者基本信息】 华中科技大学 ， 儿科学， 2013， 博士

【摘要】 背景促性腺激素释放激素（gonadotropin-releasing hormone, GnRH）在生殖功能的神经内分泌调节中起极其重要的作用。GnRH受体(gonadotropin-releasing hormonereceptor，GnRHR)位于垂体合成促性腺激素LH及FSH的促性腺激素细胞膜上。GnRHR属于G蛋白偶联受体超家族,优先与Gq/11蛋白偶联;其被GnRH类似物激活后刺激LH及FSH的合成与释放。人类GnRHR基因突变可致特发性低促性腺激素性腺功能减退症（Idiopathic Hypogonadotropic Hypogonadism，IHH)。目前，这种G蛋白偶联受体至少有19种不同突变被报道，且大部分为错义突变。目的探讨40例中国IHH患者GnRHR基因编码区突变频率及可能的基因型/表型相关性。方法低促性腺素性功能减退症（hypogonadotropic hypogonadism，HH）的诊断基于：女性≥17岁或男性≥18岁(青春期应完成16个女孩和17个男孩，如果它不能够是性腺功能减退)无性发育或性发育不完全，伴LH水平正常或低下及男性睾酮或女性雌二醇水平低下。所有患者经嗅觉测试均显示嗅觉正常。通过PCR扩增GnRHR基因编码区并进行直接测序以检测40例IHH患者及40例正常对照GnRHR基因编码区是否存在突变。结果发现一例男性完全性HH患者有位于GnRHR基因第四个跨膜区的纯合错义突变S168R, S168R突变是已报道的激素与受体的结合完全受损而致受体功能完全缺失。另一男性部分性HH患者有复合杂合突变(Gln106Arg和Arg262Gln), Gln106Arg突变位于GnRH-R第一个胞外环,该突变可降低但不会消除GnRH与其结合能力,而Arg262Gln突变位于GnRH-R第三个胞外环，其仅降低信号转导。我们发现患者的基因型和表型有良好相关性。携带纯合完全失活突变S168R的患者呈现完全性HH，而携带复合杂合突变Gln106Arg-Arg262Gln的患者呈现部分性HH。结论1．GnRHR突变可分为部分性或完全性功能失活突变。2.家族性HH患者的部分失活突变多为Q106R及R262Q。3.比较复合杂合突变与纯合突变提示其表型和对GnRH的反应与GnRHR功能受损程度相关。更多还原

【Abstract】 BackgroundGnRH plays an essential and central role in neuroendocrine control of reproductivefunction. The GnRH receptor is located on the plasma membrane of gonadotrophs, pituitarycells that synthesize the gonadotrophins LH and FSH. This receptor belongs to thesuperfamily of G protein-coupled receptors, and is preferentially coupled to the Gq/11protein; its activation by GnRH analogues stimulates the synthesis and release of LH andFSH. Human mutations in the gonadotropin-releasing hormone receptor (GnRHR) genecause normosmic idiopathic hypogonadotropic hypogonadism (IHH). At least19differentmutations have been identified in this G-protein-coupled receptor, which consist mostly ofmissense mutations.ObjectivesTo identify and determine the frequency of mutations in the coding region of thegonadotropin-releasing hormone receptor (GnRHR) gene in forty Chinese patients withnormosmic idiopathic hypogonadotropic hypogonadism (IHH) and establishgenotype/phenotype correlations where possible.MethodsThe diagnosis of HH was based on absent or incomplete sexual development after17yr. of age in girls and18yr. in boys (as puberty should be completed by16in girls and17in boys and if it doesn’t that could be hypogonadism) associated with low or normal levelsof LH in both sexes and low levels of testosterone in males and of estradiol in females. Allpatients presented with a normal sense of smell in olfactory specific test.40IHH patientsand40controls were screened for mutations in the coding sequence of GnRHR gene. Thecoding region of the GnRHR gene was amplified by PCR and directly sequenced.ResultsA missense mutation serine168arginine (S168R) located in the fourth transmembranedomain of the GnRHR gene was identified in a homozygous state in one male withcomplete HH, the S168R mutation has been previously shown to cause complete loss ofreceptor function because hormone binding to the receptor is completely impaired. In another patient, a compound heterozygous mutation (Gln106Arg and Arg262Gln) wasidentified in a male with partial HH, the Gln106Arg mutation located in the firstextracellular loop of GnRH-R, this mutation decrease but not eliminate GnRH binding,while Arg262Gln mutation located in the third extracellular loop of GnRHR and onlydecreases signal transduction. A good correlation between genotype and phenotype wasfound in our patients. The patient, who is homozygous for the completely inactivatingS168R mutation, has complete HH. In addition, the affected patient who is compoundheterozygotes for the Gln106Arg-Arg262Gln mutations, has partial HH.Conclusions1GnRHR mutations can be classified into partial or complete loss of function mutations.2Partially inactivating substitutions of the GnRHR frequently found in familialhypogonadotrophic hypogonadism are Q106R and R262Q.3Comparison of compound heterozygous with homozygous patients suggests that theirphenotype and the response to GnRH are determined by the GnRHR variant with theless severe loss of function.更多还原