Genetic studies among the Kadar of Kerala.

Abstract

A total of 213 Kadar from a number of villages in the Anamalai Hills, South India have been tested for 4 blood group, 5 serum protein and 15 enzyme systems, as well as haemoglobin. The frequencies of genes in the ABO, MN and Rh blood group systems are compatible with values reported previouslythe fourth blood group system Ina was invariant, all persons tested being In(a-). Similarly no variants were detected in the transferrin, caeruloplasmin and albumin serum protein systerns. The haptoglobin gene Hp1 had a frequency of 0.41, high for Indian populations and also the Gm-1–2allele had a high frequency. Two individuals had the rare phenotype Gm (–1, +2). Amongst the red cell enzyme systems distinctive variants were detected in the phospho-gluconate dehydrogenase, phosphoglucomutase (locus 1) and peptidase B systems. The allele PGDKadar controls an electrophoretically fast variant and examples of combinations of this allele with PGDA, PGDC and itself were observed. In the PGM (locus 1) system an allele controlling a slower than normal component was present and may be identical with the PGD61 (African) allele detected in a black African. Individuals homozygous for this allele and others heterozygous with it and the normal PGM11and PGM12alleles were present. A single person with a peptidase B variant was detected. The mobility of the variant band was indistinguishable from the Pep B 6 in Australian aboriginals. The pb allele of the acid phosphatase system accounted for nearly 90%, Calcutta-1 variants had a frequency of 3.3%, the AK2 gene frequency was only 3.3%, and only two cases of HbS were detected. All other systems were invariant. Theories concerning the origin of the possible negrito-like traits in a small number of Kadar were discussed and the present evidence was considered to support the possibility of past African negro admixture on a small scale. The postulated genetic reconstruction of the ancestral Kadar population suggests that they may have been similar to Melanesian and Australian aboriginal populations, but that this original genetic structure has been modified through incorporating genetic elements not only from black Africans but from surrounding Dravidian populations.