对法医学相关的DYS549、DYS527和DYS459基因座在男性不育症人群中的缺失、重复调查

Identification of null and duplicated alleles for forensic DYS549, DYS527 and DYS459 in male infertility population

位于Y染色体无精症因子区域(Azoospermia factor,AZF)的基因座位点DYS549、DYS527和DYS459在法医学鉴定和家系分析中被广泛应用。但是,在男性不育患者中,DYS549、DYS527和DYS459位点很可能会表现出特殊的基因型,对应用Y染色体短串联重复序列(Y chromosome short tandem repeat,Y-STR)进行个体识别的结果产生干扰。因此,文章应用14个Y-STR基因座复合扩增体系和Y染色体AZFc区DAZ、CDY1基因的拷贝数检测等方法,探讨男性不育症中法医学相关的3个Y-STR基因座的异常分型,对个体识别和家系分析中的DNA检验异常结果提供合理的解释。在240例男性非梗阻性无精、严重少精、先天性双侧输精管缺如(CBVAD)患者中,采用改良的多重PCR体系进行AZF区域微缺失的序列标签位点(Sequence tagged sites,STSs)检测,发现AZF微缺失40例(AZFa:2例;AZFb:2例;AZFc:30例;AZFb+c:6例),AZF的总缺失率为16.67%。应用14 Y-STR复合扩增体系对上述AZF微缺失的阳性患者样本进行检测,发现所有AZFb缺失患者存在DYS549等位基因缺失,AZFc缺失患者存在DYS527、DYS459等位基因缺失,AZFb+c缺失患者存在DYS549、DYS527和DYS459等位基因缺失。在AZF微缺失阴性的不育症患者中,通过检测DAZ、CDY1基因拷贝数发现10例AZFc部分复制的患者(1例为先天性输精管缺如,2例非梗阻性无精症,7例严重少精子症),占所调查不育人群的4.17%。男性不育人群AZF区域3个Y-STR基因座多态性会造成等位基因缺失或者重复,这些异常分型是由于临床遗传缺陷造成的而不是实验偏差。阐明Y-STR在男性不育人群中的异质性可以更好地完善Y-STR数据库和解释STR实验结果。

DYS549, DYS527, and DYS459 loci, located on the azoospermia factor （AZF） region and widely used in fo- rensic and pedigree analysis, may be specifically altered in infertile patients, which will obscure the result of individual identification using Y-STR （Y chromosome short tandem repeat）. In this study, we determined the AZF polymorphism by STS/- （sequence tagged site） and DAZ, CDY1 gene copy numbers, and screened the samples by 14 Y-STR loci to disclose the unusual genotype of Y-STR in male infertility population. The 240 infertile males including non-obstructive azoosper- mia, severe oligozoospermia and congenital bilateral absence of vas deferens （CBVAD） were analyzed with a modified multiplex PCR system for AZF microdeletion STSs. AZF microdeletions were found in 40 cases （16.67%） （AZFa deletion, two cases; AZFb deletion, two cases; AZFc deletion, 30 cases; AZFb＋c deletion, six cases）. Further screening by the 14 Y-STR loci in samples with microdeletions, we found DYS549 allelic loss in all the cases with AZFb deletion, DYS527 and DYS459 allelic loss in all the cases with AZFc deletion, DYS549, DYS527, and DYS459 allelic loss in all the cases with AZFb＋c deletion. Ten patients （4.17%） with AZFc partial duplication （one CBVAD case, two non-obstructive azoospermia cases, seven severe oligozoospermia cases） were found by DAZ and CDY1 gene dosage analysis. In conclusion, the unusual patterns of DYS549, DYS527, and DYS459 are caused by genetic defects rather than experimental bias. Revealing the locus heterogeneity in male infertility population can enrich the Y-STR database and assist in interpreting abnormal STR geno- type in forensic DNA testing.