β-1,3-N-乙酰氨基半乳糖转移酶基因433C＞T突变导致罕见Pk表型

A rare pk phenotype caused by a 433 C 〉T mutation of the β-1,3-N-acetylgalactosyltransferase gene

目的 探讨P1Pk血型系统中1例罕见Pk表型的血清学特征和分子机制.方法 应用血清学技术鉴定先证者血型,应用聚合酶链反应测序技术对Pk表型相关的β-1,3-N-乙酰氨基半乳糖转移酶基因（B3GALANT1）编码区及侧翼内含子区进行序列分析.结果 先证者确认为罕见的Pk表型,血清中含有抗-P抗体,其女儿、丈夫为P2表型.测序结果显示：其丈夫、2个随机样本的B3GALANT1基因序列与对照参考序列（GenBank AB050855）完全一致,而先证者的B3GALANT1基因第433位存在C＞T纯合突变,这导致在第145位氨基酸处提前形成终止密码而表达不成熟蛋白,从而可能降低或抑制1,3-N-乙酰氨基半乳糖转移酶的活性.其女儿B3GALANT1基因第433位为C/T杂合.结论 由B3GALANT1基因433位核苷酸C＞T突变导致的Pk表型在中国人群中尚未见报道.

Objective To study the serological characteristics and molecular mechanism for a rare pk phenotype of the P1Pk blood group system.Methods The blood group of the proband was identified by serological techniques.The coding region and flanking intronic sequences of the β-1,3-N-acetylgalactosyltransferase gene （B3GALANT1）associated with the pk phenotype were analyzed using polymerase chain reaction sequence-based typing.Results The proband was identified as having a rare pk phenotype including anti-P in her serum.The blood group of her daughter and husband showed a P2 phenotype.The nucleotide sequences of the B3GALANT1 gene of her husband and two randomly-chosen individuals were the same as the reference sequence （GenBank AB050855）.Nucleotide position 433 C〉T homozygous mutation in the B3GALANT1 was found in the proband,which has resulted in a stop codon at amino acid position 145,which may produce a premature protein capable of decreasing or inhibiting the activity of the β-1,3-N-acetylgalactosyltransferase.The nucleotide position 433 C/T heterozygous in the B3GALANT1 was found in her daughter.Conclusion The pk phenotype resulted from 433 C〉T mutation in the B3GALANT1 gene has been identified.