Rh血型弱D变异体的分子遗传学分析

Molecular genetic analysis of a weak D phenotype

目的分析1例Rh血型弱D型个体的分子机制。方法采用血清学方法确认样本的RhD血型表型。用PCR特异性扩增RHD基因的10个外显子，并测序分析RHD基因的全长编码序列。用PCR法测定融合Rh盒子以分析RHD基因的纯合性。结果先证者RhD血清学检测为弱阳性，其RHD基因可扩增出第1～10外显子，且为融合Rh盒子阳性，判定其基因型为RHD’／RHD一型。RHD基因外显子测序结果显示，与正常RHD基因序列相比，先证者第3外显子第365位碱基存在C〉T突变。根据血清学和基因测序结果，可将标本定义为弱D型54。结论发现1例弱D型54，其RHD基因第365位碱基的C〉T突变导致D抗原表达减弱。

Objective To explore the molecular basis for an individual with a rare weak D phenotype. Methods Serological methods were used to characterize the RhD blood group phenotype. The exons of RHD gene were amplified with PCR and sequenced. The presence of Rhesus box was tested by PCR to determine the homozygosity of RHD gene. Results The RhD blood group of the proband was detected as weak D. The 10 exons of the RHD gene and Rhesus box could be amplified by PCR, and the genotype of RHD alleles was determined as RHD＋/RHD-. The exons of the RHD gene were sequenced, and a 365C〉T mutation in exon 3 was detected. Therefore, the RhD blood group of the proband was confirmed as weak D type 54 by both serological methods and DNA sequencing. Conclusion A weak D type 54 has been detected. A 365C〉T mutation in RHD gene is responsible for the low expression of D antigen.