Investigation Of Single Nucleotide Polymorphisms In The Promoter Regions Of Pubertal Associated Genes

The sex development of puberty is defined as the transient period of body rapid development during which reproductive function is attained. During this period the adolescent growth spurt occurs, the secondary sexual characteristics appear, and the gonads start to produce mature gametes (sperm or oocytes) capable of fertilization. The large variability between individuals in the onset of puberty and subsequent developing speeds, developing levels and mature ages is determined by the integrated effects among heredity, race, nutrition and environment. Puberty is a complex trait affected by so many factors, among them genetic components play an important role in this process.Puberty begins with the reactivation of HPG axis, when the pulsatile release of GnRH increases. The GnRH released from neuroterminals in the median eminence flows from the portal circulation to anterior pituitary gland, where it subsequently acts on gonadotropins to stimulate the synthesis and release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH). These peptides in turn travel through the general circulation to the gonads, affecting the synthesis and secretion of steroid hormones, which are essential for the production of mature gametes.It may be abnormal if the onset time of sex development is much ahead or delayed. The early timing means the Precocious Puberty, children's precocious puberty is related to the hormones of HPGA. We calculated that the amount changes of GnRH, LH, FSH led to the ahead time of puberty, so we figured these genes as the major candidate genes for studying precocious and normal sex development. In this work,we used genetics candidate genes method to resequence the promotor regions of GnRH I, GnRH II ,LH β ,FSH β and find the SNPs affacted the transcription of the genes, assessed the associations between the SNPs and early puberty. We selected 27 Chinese girls with precocious puberty and 12 African normal women, used Nested- PCR method and resequenced the promotor 2000bp regions of these genes. Then we used Seqman software analysis and found 24 SNPs, 8 of them had been reported in NCBI, the other 16 SNPs were new SNPs, then we used Alibaba software for the regulating element prediction, and found there were 11 SNPs binding regulating proteins, among them, GnRH II's -164G→A, LHβ's -24A→ T, -228C→T, FSHβ's -218C→T etc. mightaffect pubertal timing;we also took a haplotype analysis of all these SNPs, whether these SNPs and haplotype genetic variations affect pubertal timing will be determined by Typing and Associated Analysis, their functions will be identified by experiments of molecular and cell biology.