1个AZFc缺失自然遗传的家系分析

目的:报告1个父子间AZFc缺失自然遗传的罕见家系,探讨该家系相同缺失类型导致不同临床表型的可能机制。方法:应用G显带技术进行染色体检查;通过对12个序列标签位点(STS)的多重PCR扩增,检测Y染色体微缺失;应用DNA测序技术检测DAZ基因在常染色体上的同源基因DAZL单核苷酸多态性(SNP)。结果:先证者及其父亲和弟弟的核型均为46,XY,且Y染色体微缺失位点完全一致,包括无精子症因子C区(AZFc)的sY152,sY157,sY242,sY254,sY255,sY239。但3者的临床表型各异:父亲具有正常生育能力,先证者及弟弟均不育,精子密度呈年龄依赖性下降,且弟弟伴左侧隐睾。SNP分析显示,3者的外显子2、3的基因型均相同。结论:该家系中相同缺失类型导致不同临床表型与DAZL基因多态性无关,可能与其他基因或环境因素有关。

Analysis of an AZFc Deletion Family with Natural Transmission

Objective: To report a rare family of AZFc deletion with natural transmission and explore the potential mechanism by which identical microdeletions cause different phenotypes.Methods: Chromosomal quantity and construction were detected by G-band,Y-chromosomal microdeletions by multiple PCR amplification for 12 sequence tagged sites(STSs,and the single-nucleotide polymorphisms(SNPs) of the DAZL gene,the autosomal homologue of deleted-in-azoospermia(DAZ) gene by DNA sequencing. Results: Chromosome analysis revealed a normal karyotype 46,XY in the father and both of his two sons and microdeletions of the full AZFc region were identical,including sY152,sY157,sY242,sY254,sY255,sY239 locus.However,the phenotypes of the affected patients were different: the father had normal fertility,but the sperm density of his two sons deteriorated age-dependently,and the younger one suffered from left cryptorchidism.SNP analysis demonstrated that two polymorphisms in exon 2 and 3 of the DAZL gene were identical in both the father and his sons.Conclusion: Identical Y-chromosomal microdeletions causing different phenotypes in this family is not associated with the polymorphisms of DAZL gene and may be related to other genes or environmental factors.