title: The Raikas - a unique combination of high prevalence of type 1 diabetes susceptibility genes and near zero incidence of the disease.
abstract: The Raikas, a camel rearing tribal group living in the Thar desert of Rajasthan has been reported with a very low incidence of diabetes. We analysed the frequency distribution of HLA alleles in this community and compared the same with the non-Raika group living in the same geographic location and also that of the healthy North Indian (NI) population. The data revealed an exceptionally high phenotype frequency of HLA-DRB1*03 in this community (53%) as compared to the non-Raika group (27.73%, p=7.9E-05) and the NI population (14.6%, p=7.65E06). Further analysis revealed the occurrence of four major DRB1*03 haplotypes in the Raikas: (i) A*26-B*08-DRB1*03 (AH8.2, 11.76%); (ii) A*24-B*08-DRB1*03 (AH8.3, 8.82%); (iii) A*02-B*08-DRB1*03 (3.78%); (iv) A*01-B*08-DRB1*03 (AH8.1v, 0.84%); all of which occurred with a several fold higher frequency in the Raikas than the other two groups. These haplotypes have been reported to be positively associated with T1D in the NI population. The apparent lack of T1D and/or other autoimmune diseases in the Raikas despite the higher occurrence of known disease associated HLA alleles/haplotypes is intriguing and highlights the quintessential role of the environmental factors, food habits and level of physical activity in the manifestation of T1D. Possible influence of other protection conferring genes located on, as yet undefined chromosomal locations cannot be ruled out.
authors.affiliation: Department of Transplant Immunology and Immunogenetics, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Deepali K
authors.initials: DK
authors.lastname: Bhat
authors.affiliation: Department of Transplant Immunology and Immunogenetics, All India Institute of Medical Sciences, New Delhi, India. Electronic address: umakanga@hotmail.com.
authors.forename: Uma
authors.initials: U
authors.lastname: Kanga
authors.affiliation: Department of Transplant Immunology and Immunogenetics, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Neeraj
authors.initials: N
authors.lastname: Kumar
authors.affiliation: Department of Medicine, SP Medical College, Bikaner, Rajasthan, India.
authors.forename: R P
authors.initials: RP
authors.lastname: Agrawal
authors.affiliation: Department of Transplant Immunology and Immunogenetics, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Manish
authors.initials: M
authors.lastname: Mourya
authors.affiliation: Department of Biostatistics, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Mani
authors.initials: M
authors.lastname: Kalaivani
authors.affiliation: Indian Council of Medical Research, Ansari Nagar, New Delhi, India.
authors.forename: Tanvir
authors.initials: T
authors.lastname: Kaur
authors.affiliation: Department of Transplant Immunology and Immunogenetics, All India Institute of Medical Sciences, New Delhi, India. Electronic address: narin98@hotmail.com.
authors.forename: Narinder K
authors.initials: NK
authors.lastname: Mehra
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003922:Diabetes Mellitus, Type 1 / Q000453:epidemiology* / Q000235:genetics*; D005260:Female; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D059811:HLA-DRB1 Chains / Q000235:genetics*; D006801:Humans; D007194:India / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D044382:Population Groups; D055815:Young Adult
chemical_list: D059811:HLA-DRB1 Chains
keywords: Camel milk; HLA; Haplotypes; Raika community; Type1 diabetes