HLA‐DRB1*, ‐DQB1* in Piramalai Kallars and Yadhavas, two Dravidian‐speaking castes of Tamil Nadu, South India

Abstract

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-DRB1*15011, 0301, -DQB1*0201, 0501 and 0601; YDs, HLA-DRB1*0301, 0401, 07 and -DQB1*0601; and the random panel, DRB1*15021, 0401, 07, -DQB1 0201, 0301, 0302 and 0501. The highest frequency of DRB1*1501 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 DRB1*10-DQB1*0501, 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.

Suboptimal Performance of IgG Anti-tissue Transglutaminase in the Diagnosis of Celiac Disease in a Tropical Country

“…The reason for this has been attributed to the predominance of wheat as the staple diet in the northern and eastern parts of India whereas rice forms a major part of the diet in southern India. Also, the HLA susceptibility loci differ between these regions [34,35].…”

HLA Antigens in Nadars a Native Dravidian Caste Group of Tamil Nadu, South India

“…A newly arisen favorable variant allele might co-exist with the parental allele rather than replacing it when selective forces favoring diversity is operating. Recently novel alleles in the Indian populations have been reported for HLA A2, A19, B27 and DR2 alleles (Shankarkumar et al 2002a, b;Mehra et al 2001;Shanmugalakshmi et al 2003;Shankarkumar 2003;Kankonkar et al 2003).…”

“…Further various populations and caste of South India studied revealed HLA antigen disease associations as well (Brahmajothi et al 1991;Ravikumar et al 1999;Shanmugalakshmi et al 2003). Here we present the HLA polymorphism of Nadars living in Virudhunagar District of Tamil Nadu and compared them with results of selected populations of India and World.…”

Association of HLA and TNF polymorphisms with the outcome of HBV infection in the South Indian population

“…Besides, wide variations in the frequency distribution of these alleles are known to occur in the South Indian castes and tribes. 24,25 We speculate that this variation may impact the epidemiology and outcome of HBV infection in the South Indian population. However, this requires study with larger sample size including various ethnic groups of the South Indian population.…”