中国人群中发现的主要弱D型——弱D15个体的分子背景研究

为了探讨中国汉族人群弱D15型个体的Rh血型系统血型血清学表型及分子背景，采用常规血型血清学技术检测RhD抗原弱阳性个体RhD、C、c、E、e抗原表型；采用序列特异性引物-聚合酶链反应（SSP—PCR）方法同时检测RHD基因和RHCE基因；标本测序分析RHD基因全长编码区序列；同时通过特异性PCR技术测定RHD合子型或RHD基因数目。结果表明，血型血清学试验证实为D抗原弱阳性表型的人群中，有18例为弱D15型（占D抗原弱阳性表型56％），RHD基因全长编码区序列分析发现其第6外显子有一处碱基突变：845G〉A，编码区序列其它部分与正常RHD序列相同；检测Rh小因子有3种表型CcEe（2例）、CcEe（2例）、ccEe（14例），分别占弱D15型的11％、11％、78％，血清学检测结果与分子生物学检测结果一致。RHD杂合性试验鉴定显示仅表型为CcEe的2例标本为纯合型RHD^＋／RHD^＋，提示基因型为DCe／DcE；其余为杂合型RHD^＋／RHD^-，提示基因型分别是DCe／dce和DcE／dce。结论：弱D15型是中国人群中最主要的弱D型，其中大部分为杂合型。

Molecular Background of Weak D Type 15 as the Predominant Weak D Type Found in Chinese Population

This study was aimed to investigate the molecular genetic basis and serological phenotype of Rh weak D type 15 individuals. Samples were identified by serological tests and genotyped by sequence specific primer-PCR (SSP-PCR), and were sequenced to detect the changes of all ten RHD exons. The number of gene RHD was detected through SSP-PCR. The results showed that in tested individuals of weak D type confirmed by the IAT, 18 cases (56% in weak D) were weak D type 15. Rh factors found in 2 weak D type 15 individuals (11%) were C+c+E+e; Rh factors found in 2 weak D type 15 individuals (11%) were C+c+E-e+; others (78%) were c-c+E+e+. The results by serological tests were consistent with the results genotyped by PCR-SSP method. In all 18 samples, the sequencing result revealed a gene mutation 845G > A at the exon 6 of the RHD and the point mutation changed amino acid G282D of the RhD polypeptide. The zygosity test demonstrated that 2 out of 18 weak D type 15 individuals were RHD(+)/RHD(+) homozygous (two DCe/DcE), 16 cases were RHD(+)/RHD(-) heterozygous (two DCe/dce and fourteen DcE/dce). It is concluded that Weak D type 15 is predominant in weak D individuals of Chinese Han Nationality, and most of them are heterozygous with various RH haplotypes.