一例B303亚型的鉴定及家系遗传分析

Identification and pedigree analysis of ABO subgroup B303

目的对1例AB0正反定型不符的标本进行血型血清学鉴定，并探讨其ABO基因的分子机制。方法分析该家系2代共5例标本，ABO表型采用血型血清学试验，通过对1例B亚型先证者和4例家系成员ABO基因第6、7外显子和第3内含子的测序分析来确定其基因型。结果5例家系成员中有4例亚型：3例为AB3亚型，1例为B3亚型。基因型分型分别为A102／B303和002／B303。DNA序列分析显示，与B101相比，B303存在第3内含子＋5G〉A突变。结论第3内含子的＋5G〉A位点的点突变是B303的特异性突变。

Objective To explore the molecular mechanism of a case of ABO discrepancies based on the results of blood group serology. Methods Five cases of the two generation pedigrees were analyzed. ABO genotypes were determined using serological tests. DNA sequence analysis was performed on exon 6, exon 7 and intron 3 of the 5 cases to confirm the genotypes of a proband with B subgroup and 4 family members. Results There were 3 cases of subgroup AB3 and 1 case of subgroup B3 among the 5 family members. The genotypes were identified as A102/B303 and O02/B303, respectively. B303 differed from B101 by intron 3 point mutation （intron3 ＋ 5G〉A）. Conclusion The point mutation of intron 3 （intron 3 ＋5G〉A） is specific in B303.