A3等位基因的分子遗传分析

为了研究血型血清学鉴定为A3型的4例样本，其中2例样本为一个家系，用血清学方法检定其3例为A3型，1例为A3B型。通过PCR-SSP与测序分析其Exon 6与Exon 7及部分内含子，与A101等位基因参比序列进行了比较。结果发现在2例A、型样本中单倍体分别为常见的A102等位基因与O1—2等位基因，1例A，样本中单倍体分别为常见的A102等位基因与少见的O^1V-4等位基因，1例A3B样本在A基因中发现838C→T(Leu280Phe)，此研究结果提示血清学表现为A3型的分子遗传背景存在多态性，A3B型的838C→T可能是A3低转移酶活性的分子基础。

Molecular Genetic Analysis for the A3 Alleles

To study four A(3) subgroup samples identified by serologic tests, among which two belong to a family, three were A(3) subgroup, one was A(3)B subgroup. All four samples were genotyped by PCR-SSP method, and the nucleotide sequences of Exon 6, Exon 7 and part introns at the ABO locus for these samples were detected by ABI Prism 3100 DNA sequencer. Comparison with the consensus of A101 was performed. The results showed that haplotypes of two A(3) subgroups were common A102 allele and O1-2 allele, and haplotypes of one A(3) subgroup were common A102 allele and rare O(1v)-4 allele. Unexpectedly, a synonymous substitution 838C-->T had been found in A allele of the A(3)B subgroup sample, which predict a Leu280Phe alteration. The results suggested that molecular genetic background of the A(3) phenotypes is polymorphic. Possibly, the missense mutation 838C-->T is the molecular genetic basis of A(3)B subgroup that lead to low activity of the glycosyltransferases.