B抗原减弱表型的表型频率与ABO基因分析

目的对血清学表现为B抗原减弱的血液样本进行筛查和ABO基因分析，了解其分布特征和分子遗传学基础。方法筛查并收集B抗原减弱（与抗-B血清试管法凝集强度中等）的样本，采用血型血清学方法进行鉴定分析，采用直接测序的方法对ABO基因的第6、7外显子及第6内含子进行序列分析，对可追踪家庭进行家系分析。结果从241952份样本中检出13例B抗原减弱表型，其中B型9例、AB型4例；所有样本的红细胞与抗-H反应均增强；其中2例可检出不规则抗-B；ABO基因型分别为A102／Bw12（1例）、BIOI／B101（2例）、B10I／002（3例）、A102／B101（3例）、B101／001（4例）。在1例基因型为B101／001个体的家系成员（父亲）中检出相同表型。结论该类表型在B型人群中的频率约为1：7000；除1例样本的B等位基因存在278C〉T突变（Bw12）外，其余样本在第6、7外显子和第6内含子中均未检出突变；ABO基因酶催化活性区域编码序列以外的基因变异，可能是导致B抗原减弱的原因之一。

Analysis on the frequency of weak B phenotype and molecular genetics on ABO gene

Objective To study the frequency of weak B phenotype and analyze the molecular genetics on ABO gene, and to analyze the serological and genetic characteristics. Methods The samples with B phenotypes （ moderately agglutinate by anti-B） were identified, screened and collected by the serological techniques in routine ABO blood group. The sequences of exon 6 ,exon 7and intron 6 of ABO gene were analyzed by direct DNA sequencing. Pedigree study was performed in traceable family. Results A total of 13 weak B phenotypes were observed in 241 952 cases （9 cases of blood group B and 4 cases of blood group AB）. Enhanced agglutination with anti-H was observed in all the sample＇s red cell. The ABO genotypes of A102/Bwl2 ,B101/B101 ,B101/O02 ,A102/B101, B101/O01 were detected in 1,2,3,3 and 4 of the 13 cases. A same weak B phenotype was detected in a B101/O01 family （father） study. Conclusions The frequency of weak B phenotype in Fujian population with B blood group is about 1：7 000. A B allele with a nucleotide 278C 〉 T mutation （Bwl2 ） is detected, and no mutation is detected among the others for exon 6, exon 7 and intron 6. Variations outside the sequence of glycosyltransferase catalytic domain may be the factors for weak B phenotype.