Shanmugalakshmi S, Balakrishnan K, Manoharan K, Pitchappan R M
Department of Immunology, Centre for Advanced Studies in Functional Genomics, School of Biological Sciences, Madurai Kamaraj University, Madurai 625 001, India.
Tissue Antigens. 2003 Jun;61(6):451-64. doi: 10.1034/j.1399-0039.2003.00061.x.
Two Dravidian-speaking castes of Tamil Nadu, Piramalai Kallars (PKs, n = 205) and Yadhavas (YDs, n = 239) and a random panel (84) were studied for HLA-DRB1* and -DQB1* polymorphisms by DNA-SSOP typing methods. XI and XII International Histocompatibility primers and non-radioactive-labelled oligo probes were employed to identify the alleles. Results revealed that PKs possessed >0.1 allele frequencies of HLA-DRB115011, 0301, -DQB10201, 0501 and 0601; YDs, HLA-DRB10301, 0401, 07 and -DQB10601; and the random panel, DRB115021, 0401, 07, -DQB1 0201, 0301, 0302 and 0501. The highest frequency of DRB11501 in the world (GF = 0.225) was found in PKs. The most frequent two-locus haplotype (>500/10,000) in all the study samples was DRB110-DQB10501, while 1501-0601 was frequent in PKs and YDs. Comparison of the HLA-DRB1* data with Eastern European and South-East Asian populations suggested migration as the prime cause of the observed diversity in DRB1* allele frequencies. Nonetheless, the heterozygocity test and Watterson's homozygosity test indicated that balancing selection still operates on HLA-DRB1* locus, in this endemic region of various infectious diseases. This and spatial autocorrelation analysis support the view that selection may be a cause of "generating" new variants and allelic diversity in different ancient settlements. The study suggested that South Indian, inbred, endogamous, sympatrically isolated castes or similar well-defined breeding isolates around the world, living under the same milieu-epidemiology, may be ideal models to test the immunogenetic basis of disease susceptibility.
通过DNA-SSOP分型方法，对泰米尔纳德邦两个说达罗毗荼语的种姓——皮拉马莱卡拉尔人（PKs，n = 205）和雅达瓦人（YDs，n = 239）以及一个随机样本（84人）进行了HLA-DRB1和-DQB1多态性研究。使用第十一和第十二届国际组织相容性引物以及非放射性标记的寡核苷酸探针来鉴定等位基因。结果显示，PKs拥有HLA-DRB115011、0301、-DQB10201、0501和0601的等位基因频率>0.1；YDs拥有HLA-DRB10301、0401、07和-DQB10601；随机样本拥有DRB115021、0401、07、-DQB1 0201、0301、0302和0501。在PKs中发现了世界上DRB11501的最高频率（基因频率=0.225）。所有研究样本中最常见的两位点单倍型（>500/10,000）是DRB110-DQB10501，而1501-0601在PKs和YDs中较为常见。将HLA-DRB1数据与东欧和东南亚人群进行比较表明，迁移是观察到的DRB1等位基因频率多样性的主要原因。尽管如此，杂合性测试和沃特森纯合性测试表明，在这个各种传染病的流行地区，平衡选择仍然作用于HLA-DRB1*基因座。这一点以及空间自相关分析支持了这样一种观点，即选择可能是在不同古代定居点“产生”新变体和等位基因多样性的一个原因。该研究表明，南印度的近亲、族内通婚、同域隔离的种姓或世界上其他类似的明确界定的繁殖隔离群体，生活在相同的环境流行病学条件下，可能是测试疾病易感性免疫遗传基础的理想模型。
