Immunoglobulin (GM and KM) allotypes in the Sikh population of India

Abstract

The populations of India are genetically diverse, both within and between geographic regions; immunoglobulin (GM) allotypes provide important information on genetic differences between populations, since the frequencies of combinations of allotypes (termed "haplotypes") vary dramatically among ethnic groups. As part of a project to assess genetic diversity among defined Indian populations, we have examined eight GM allotypes in a sample of 101 unrelated Sikhs who have migrated to Toronto, Canada: Glm(1, 2, 3, 17) and G3m (5, 15, 16, 21). Sikhs are a religious group that arose in the Punjab about 1500 A.D.; most of the original converts are believed to have been middle to upper-middle caste Hindus. Gm allotyping showed that six Gm haplotypes occurred at polymorphic frequencies (greater than 0.01) in Sikhs: Gm3;5, Gm1,17;21, Gm1,2,17;21, Gm1,17;5, Gm1,17;15,16, and Gm1,3;5. These haplotypes have all been previously reported in Indian populations. The frequencies of the first four haplotypes resembled the published frequencies for lower-caste Hindus of NW India more than upper-caste Hindus. However, the last two haplotypes have been found only in upper-caste Hindus. The frequency of one of these, Gm1,17;15,16 was higher in Sikhs (0.09) than has been reported in any Indian population with the exception of Parsis (who are descended from Iranians). We speculate that the high frequency of this haplotype may have been characteristic of some of the Hindu castes in the Punjab from which Sikhs are descended.

GM and KM allotypes in eight tribal populations of madyha Pradesh and Orissa, India

“…Sikhs or Muslims) is either very low or they are even completely absent. This follows from studies on Punjabis (Daveau et al, 1980), higher and lower caste Hindus from Northwest India (Schanfield and Kirk, 1981), upper-caste Hindus from Bengal (Ray and Field, 1981), Sikhs (Field et al, 1988), and Brahmins, Kalitas, Kaibartas, and Muslims from Assam (Walter et al, 1987). All these population groups are characterized by the clear prevalence of the "Caucasoid" array of GM haplotypes, namely GM'1,17;21,26;GM* 1,2,17;21,26;and GM'3;5,10,11,13,14,26.…”

“…Concerning the occurrence of "Mongoloid" GM haplotypes in the Assamese caste and community populations Walter et al (1987) suggested some gene flow from Mongoloid side, which could be substantiated considering the ethnohistory of Assam. The occurrence of "Mongoloid" haplotypes in Sikhs was explained by the possibility, that they may have characteristic of some of the Hindu castes in the Punjab, from which the Sikhs are descended (Field et al, 1988).…”

“…At any rate larger samples from the various caste groups in that region are needed to provide more information relevant to that possibility as Field et al (1988) suggested. The fact is in any case that "Mongoloid" GM haplotypes are more or less rather frequent in all Indian tribal populations.…”

“…Therefore, in view of the complexity of the GM polymorphism, our knowledge concerning the distribution of GM allotypes among Indian populations is still limited. Larger sets ofGM allotypes have been examined so far only by Daveau et al (1980), Ray and Field (1981), Schanfield and Kirk (1981), Field et al (1988) and Walter et al (1987).…”

Gm and Km allotypes in four Sardinian population samples

“…In Asia, however, especially in the northeastern parts of India (Assam), this Mongoloid haplotype was also found among several populations of Caucasoid origin, which suggests that some genetic contact with Mongoloid populations living there had taken place . Field et al (1988) observed this haplotype in a Sikh sample (from Canada, but originating from Northwest India). This suggests a larger distribution of this Mongoloid haplotype in Asia than so far supposed, and its actual distribution especially in Western Asia including the Middle East should be more thoroughly reviewed therefore.…”