α-1,3-N-乙酰半乳糖胺转移酶p.Trp181Cys突变导致Aw亚型

Aw subtype formation by α-1,3-N-acetylgalactosamine transferase p.Trp181Cys mutation

目的探讨Aw亚型的血清学特征和分子生物学机制。方法采用标准血型血清学方法检测先证者及其家系(父亲、母亲、女儿、儿子)ABO血型,利用聚合酶链反应(PCR)特异性序列引物对先证者及其父亲进行ABO基因初步分型,再使用PCR方法扩增ABO基因7个外显子的全部编码序列并进行测序。结果该家系成员中有2例为Aw亚型,其红细胞含有弱A抗原,血清中含有抗A和抗B,基因型为Aw.new/O01;2例为B亚型;1例为O亚型。ABO血型基因直接测序分析显示先证者及其父亲存在c.467C>T、c.543G>C杂合变异和c.261delG缺失。第7外显子发生543位碱基G>C突变,导致第181位氨基酸由色氨酸被半胱氨酸替换,该突变极其罕见。结论α-1,3-N-乙酰半乳糖胺转移酶基因第543位G>C突变可能引起酶活性下降,从而导致A抗原表达减弱,该研究进一步证实该突变具备遗传基础,在家系中能够稳定遗传。

Objective To explore serological characteristics and molecular mechanism of Aw subtype.Methods The ABO antigen and serum antibody of the proband and her family members(her father,mother,son and daughter)were detected by standard serological method.The ABO gene of the proband and her father were detected by polymerase chain reaction(PCR)method using sequence specific primers.Exons 1 to 7 of the ABO gene was amplified and sequenced with PCR method.Results Among the family members,2 cases were Aw subtype,weakened A antigen was detected on red blood cells of them,both anti-A and anti-B were detec-ted in the serum,and their genotypes were Aw.new/O01;2 cases were B type;1 case was O type.Direct se-quencing analysis of ABO blood type gene showed that the proband and her father were heterozygous for c.467C>T,c.543G>C,in addition with a c.261G deletion.The mutation c.543G>C in exon 7,which caused a-mino acid from tryptophan to cysteine at position 181.The mutation is extremely rare.Conclusion The muta-tion c.543G>C ofα-1,3-N-acetylgalactosamine transferase gene may reduce enzyme activity and the expres-sion of A antigen,and the study further confirms that the mutation can be stably inherited in the family.