一例Ah-分泌型个体的分子生物学背景的分析

Analysis on the molecular basis for an Ah-secretor individual

目的研究Ah-分泌型个体的分子基础。方法经血型血清学方法鉴定红细胞上H抗原缺失、但存在弱A抗原的Ah-分泌型个体,用PCR-SSP法鉴定ABO基因型,对FU-T1和FU-T2编码区域进行扩增,并对扩增产物直接测序,FU-T1进一步做克隆测序分析。结果血清学结果显示该个体红细胞不凝集抗H血清,但与抗A定型血清呈弱凝集,Lewis血型表现型为Le(a-b+),唾液中有A、H物质,ABO基因型为A102B02;FU-T1基因型为h35h328,h35等位基因(nt35C>T),使12位(Ala)丙氨酸被(Val)缬氨酸置换;h328等位基因(nt328G>A),导致110位Ala(丙氨酸)被Thr(苏氨酸)置换;FU-T2基因为正常野生型Se357Se357。结论两个错义突变C35T、G328A可能是引起该例Ah-分泌型H抗原缺失、但存在A抗原的弱表达的原因。

Objective To analyze the molecular basis in an Ah-secretor individual. Methods Serological investigation of an Ah-secretor individual was characterized using standard techniques. ABO genotype was detected by PCR-SSP, and the entire coding region of FU-T1 gene and FU-T2 gene was amplified by polymerase chain reaction, then through direct sequencing for the products of FU-T1 and FU-T2 genes. Furthermore, molecular cloning sequence of FU-T1 gene was analyzed. Results The serological results showed that red blood ceils of the Ah-secretor individual were not agglutinated by anti-H typing reagent, but could be weakly agglutinated by anti-A typing reagent. Lewis blood group phenotype was Le（a-b＋）. The A substance was found in her saliva. ABO genotype was A102B02. The FU-T1 genotype of the Ah-secretor individual was h^35h^328. Two missense mutations of FU-T1 gene were found, nt35C〉T induced a change of Ala12 to Val, and nt328G〉A induced a change of Ala110 to Thr. The FU-T2 genotype was Se^357Se^357. Conclusion Two missense mutations of FU-T1 gene, C35T and G328A may be responsible for H-deficient, which indirectly lead to weak expression of A antigen.