中国人副孟买型的FZ／T1和FUT2基因的分子遗传研究：一个新的FZ／T1等位基因的鉴定

Molecular genetic analysis of FUT1 and FUT2 gene in para-Bombay Chinese： a novel FUT1 allele is identified

目的在7例由血清学方法确定为副孟买表型的中国人个体中，进行了分子生物学分析。方法采用聚合酶链反应和DNA直接测序、克隆测序等方法，检测7例标本的FUTl和FUT2基因的核苷酸序列组成，并对一个新的非功能性FUTl等位基因进行家系调查。结果7例标本的FUTl基因型分别为hlhl（4例），h2h2（2例），h^328 h^new（1例），hl等位基因在547～552位缺失1个AG，使得氨基酸序列发生182框码移位；b2等位基因在880～882位缺失两个T，使得氨基酸序列发生294框码移位；h^32S等位基因（nt328G〉A）导致110位丙氨酸（Ala）被苏氨酸（Tnr）置换；除h一以外，hl、h2、h^32S这3种等位基因以前都有报道，h^new以杂合子形式存在于标本7中，经克隆测序发现该新基因在nt36m400位缺失GGTATTCCGCATCACCCTGCCCGTGCTGGCCCC,共33个碱基，家系调查证明h^new来自其母亲。7例标本的FUT2基因型分别为，3例为正常野生型Se^357 Se^357，3例标本为Se^357 Se^357,385，1例标本为Se^357,716 Se^357,716，已知Se^357（nt357C〉T）和Se^716（nt716G〉A）为功能性的FUT2等位基因，Se385（nt385A〉T）为弱功能性的FUT2等位基因，7例副孟买表型个体至少带一个拷贝的功能性FUT2等位基因，与其分泌状态一致。结论发现一个新的非功能性FUT1等位基因，其在nt36-400位缺失33个碱基，引起氨基酸序列框码移位，不能编码有活性的H抗原转移酶。

Objective Molecular genetic analysis of FUT1 and FUT2 gene was performed for seven Chinese Han individuals serologically typed as para-Bombay. Methods Seven DNA samples were studied by polymerase chain reaction and then by direct sequencing. Molecular cloning sequencing was done for a individual with a novel FUT1 allele. Family segregation analysis of the novel FUT1 allele was done to explore whether the allele was responsible for the fucosyltransferase defects of H. Results The FUT1 genotypes of seven para-Bombay individuals were hlhl （four individuals）, h262 （two individuals）, h^328 h^new（one individual）, alleles hl lost one of the three AG repeats located at the nucleotides 547-552 of the FUT1 gene, h2 lost two of the three T repeats located at the nucleotides 880-882, h^328 （nt328G〉 A） was a missense mutation, all of them were known mutations, while allele h^new deleted GGTATYCCGCATCACCCTGCCCCGTGCTGGCCCC at nt360-400, total 33 bases, and the frame-shift mutation was not previously reported. The segregation of the h^new allele in his family showed that his father genotype was Hh32s, and his mother was Hh^new, while two brother were h^328 h^new. The FUT2 genotypes of seven para-Bombay individuals were Se^357 Se^357 （ three individuals）, Se^357 Se^357,385 （ three individuals）, Se^357,716 Se^357,716 （ one individual）, the functional Se^357 （ nt357C 〉 T）, Se^716 （nt716G〉 A） and the weakly functional Se^385（nt385A〉 T） were known. The seven para-Bombay individuals carried at least one copy of a functional FUT2 allele was consistent with their secretor status. Conclusion A novel FUT1 allele was identified in a para-Bombay Chinese individual, which was responsible for the inactivation of the FUT1 -encoded enzyme activity.