罕见cisAB血型家族的遗传学分析

Genetic analysis of a family with the rare cisAB phenotype

目的 cisAB是一种罕见的ABO表型,常表现为正反定型不符。文中对1例在常规血型鉴定中发现的罕见cisAB血型及其家族成员进行鉴定。方法抽取先证者及其家族成员共计7人的外周抗凝血液,采用试管法分析血型血清型;以PCR-SSP基因分型法和直接测序法分析这些样本的ABO基因。结果血清学方法证实该家系6份样本的红细胞都有接近正常的A抗原和较弱的B抗原,血清中含有弱的抗-B抗体。PCR-SSP基因分型显示该6份样本均为cisAB01型。ABO基因测序结果:6份样本的第7外显子均存在467C>T和803G>C点突变;在第6外显子,先证者出现261delG和297G>A,2例标本出现261delG和297AA,3例标本表现为只有297AA。结论该家系6名成员的表型均为cisAB01型,先证者基因型为cisAB/O02。

Objective CisAB is a rare ABO phenotype usually with discrepancy between forward and reverse ABO typing. This study aims to verify a 35-year-old male with the cisAB phenotype identified during routine ABO blood grouping and his family members. Methods Blood samples were collected from the proposita and his family members. Routine ABO blood grouping was car- ried out using the tube method. The ABO gene of the samples was analyzed by genotyping with polymerase chain reaction-sequence-specific primer （PCR-SSP） and direct sequencing. Results Serological identification of the 6 samples of the family showed the expression of nearly normal A antigen and relatively weak B antigen in the red blood cells. Sera from these samples contained weak anti- B antibodies. ABO genotyping revealed a cisAB01 phenotype in all these samples. Two point mutations in exon 7 of the ABO gene were identified from the samples by direct sequencing： 467C 〉 T and 803G 〉 C. As for exon 6, the proposita had 261delG and 297G 〉 A, 2 members had 261de1G and 297AA, and the other 3 had 297AA only. Conclusion The genetic findings indicated the cisAB01 phenotype in the 6 members of the family and the cisAB/O02 genotype in the proposita.