一例罕见AB类孟买血型的鉴定分析

目的：对一例AB类孟买血型的先证者进行血型血清学鉴定和分子生物学机制研究。方法：采用血型血清学技术分别对先证者红细胞上ABH抗原、唾液中ABH血型物质、红细胞上Lewis抗原及血浆中红细胞不规则抗体进行检测；采用PCR技术分别扩增先证者ABO 基因第6、第7外显子及FUT1、FUT2 基因全部编码区域，PCR产物纯化后直接测序，通过Chromas软件与人类红细胞血型基因数据库进行基因序列比对，查找突变位点。结果：血清学实验结果表明，先证者红细胞上检到弱A抗原、Leb抗原，未检到B抗原、H抗原及Lea抗原，唾液中检到A、B、H血型物质，血浆中检到IgM类抗HI抗体。DNA测序结果显示先证者ABO 基因型为*A1.02 /*B.01；FUT1 基因存在c.551_552delAG杂合缺失突变及c.881_882delTT杂合缺失突变，FUT2 基因存在c.357C＞T纯合多态性。结论：FUT1 基因双杂合缺失突变是导致先证者为AB类孟买血型的主要原因。

Identification and analysis of a rare clinical case with AB and para-Bombay phenotype

Objective: To explore serological identification of blood type and genetic basis of a proband with para-Bombay AB blood type. Methods: ABH and Lewis antigens on the red blood cell (RBC), RBC irregular antibodies in plasma and the ABH blood group substances in saliva were detected by standard serologic techniques.Exons 6 and 7 of the ABO gene and exons of FUT1 and FUT2 genes were subjected to direct sequencing, and PCR amplification products were compared with the gene reference sequence to analyze the mutation sites by blast. Results: Serologic reaction results revealed that A and Leb antigens were present on the surface of RBCs from the proband, but B, H and Lea antigens were absent. A, B and H antigens were present in saliva, and the serum contained anti-H IgM antibody. The proband was proven to be a *A1.02/*B.01-type ABO gene carrier,DNA sequencing revealed that she has harbored c.551_552delAG and c.881_882delTT, and c.357C>T compound heterozygous variants of the FUT1 gene, and c.357C>T homozygous point mutation was revealed in FUT2 gene. Conclusion: Heterozygous deletion of FUT1 genes were responsible for the Para-Bombay phenotype found in secreted AB type-proband. The para-Bombay blood type ABmh phenotype of the proband may be attributed tothe FUT1 gene compound heterozygous variants.