中国汉族白血病患者及其相关人群罕见的HLA-DR/DQ连锁不平衡研究

Linkage disequilibrium between HLA-DR and -DQ loci in Chinese Han patients with leukemia and their relative donors

目的研究中国汉族白血病患者及其相关人群罕见的HLA-DR/DQ连锁不平衡单倍型。方法对2000-2005年在我院进行异基因造血干细胞移植前HLA配型的白血病患者及与患者有血缘关系的家系供者共1500例的血液标本,采用低分辨序列特异性引物聚合酶链反应(PCR-SSP)方法进行HLA-DR/DQ基因分型,并对两位点间连锁不平衡参数进行统计学分析。1500例中患者650例,平均年龄25岁;家系供者850例,平均年龄42岁。结果在41例的血液标本中发现13种罕见的连锁不平衡单倍型,主要为HLA-DQ8或HLA-DQ9与不同DR位点的连锁。其中DR14/DQ4、DR4/DQ5、DR9/DQ6、DR9/DQ7、DR8/DQ8、DR9/DQ8、DR12/DQ8、DR13/DQ8和DR14/DQ9共9种单倍型尚未见报道。650例白血病患者中有20例存在12种罕见的连锁不平衡单倍型,850例家系供者中有21例存在8种罕见的连锁不平衡单倍型。DR8/DQ8单倍型只见于家系供者,而DR14/DQ4、DR12/DQ6、DR11/DQ8、DR13/DQ8和DR14/DQ9单倍型则只见于白血病患者。41例HLA-DR/DQ基因分型结果显示,连锁不平衡单倍型与DR52(DRB3)宽抗原相关联者占58.5%(24/41),与DR53(DRB4)宽抗原相关联者占36.6%(15/41),而与DR51(DRB4)宽抗原相关联者仅占4.9%(2/41)。所发现单倍型频率最高的为DR12/DQ8(0.0023)和DR9/DQ8(0.0023),其次为DR11/DQ9(0.0020)和DR12/DQ9(0.0017)。13种连锁不平衡单倍型的绝对及相对连锁不平衡参数均为负值,说明它们在中国汉族人群中较为罕见,并处于连锁不稳定状态。结论发现了罕见的DR/DQ连锁不平衡单倍型,对补充中国汉族人群HLA-DR/DQ基因的连锁不平衡类型,提高HLA分型结果的准确性具有一定意义;同时,DR/DQ连锁不平衡单倍型在不同人群中的差异为疾病关联研究提供了思路。

Objective To investigate linkage disequilibrium (LD) between HLA-DR and -DQ loci in Chinese Han patients with leukemia and their relative donors. Methods From 2000 to 2005, 1500 blood samples were collected from 650 patients with leukemia (mean age 25 years) and 850 relative donors (mean age 42 years) before an allogeneic hematopoietic stem cell transplantation. All the samples were genotyped for HLA-DR and -DQ loci by low resolution sequence-specific primer PCR. The LD between the two loci was analyzed statistically. Results Among the 1500 samples, we discovered 13 rare patterns of LD between HLA-DR and -DQ loci in 41 cases, in most of which HLA-DR8/DR9 was combined with HLA-DQ. Nine of the 13 haplotypes were first reported (DR14/DQ4, DR4/DQ5, DR9/DQ6, DR9/DQ7, DR8/DQ8, DR9/DQ8, DR12/DQ8, DR13/DQ8, DR14/DQ9). In the 650 patients with leukemia, 12 rare haplotypes were detected in 20 cases, while 8 haplotypes were discovered in 21 of the 850 relative donors. The DR8/DQ8 haplotype was detected only in the relative donors, whereas, the DR14/DQ4, DR12/DQ6, DR11/DQ8, DR13/DQ8, and DR14/DQ9 haplotypes merely exist in the patients with leukemia. Genotyping showed that the haplotypes were associated with broad antigen DR52 (DRB3) in 58.5% of the 41 cases (24/41), with DR53 (DRB4) in 36.6% (15/41), and with DR51 (DRB4) in 4.9% (2/41). The most frequent haplotypes were DR12/DQ8 (0.0023) and DR9/DQ8 (0.0023), and DR11/DQ9 (0.0020) and DR12/DQ9 (0.0017) in the next. The absolute and relative LD parameters of the 13 haplotypes were all negative indicating that they are rarely encountered in Chinese Han population. Conclusions We found a group of rare patterns of LD between HLA-DR and -DQ loci that replenish the data of LD in Chinese Han population. The results may improve the accuracy of HLA class II matching, and provide basis for further study of HLA associated diseases.