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A Cellogel procedure for screening the electrophoretic variants of the human red cell glutathione peroxidase ( GPX1 ) was described. Three hundred and ninety eight Dutch persons living in various parts of The Netherlands, 385 individuals born in various states of India, and 72 Jamaicans of African origin living in Birmingham, UK, were screened for GPX1 variants. The Dutch were monomorphic, while one Afro-Jamaican female and two males and one female of the 116 Punjabis were found to be variants indistinguishable from each other in their pattern of electrophoresis. The clear five banded pattern of the variant indicated that the subunit structure of the human red cell glutathione peroxidase is most probably a tetramer and suggested that the variant is the expression of a heterozygote due to alleles at an autosomal locus. The corresponding phenotype was designated tentatively as GPX1 2-1 and the alleles as GPX1 *1 and GPX1 *2 respectively. The variant 2-1 was found to be identical to the "Thomas" variant described by Beutler and West (1974). Thus so far, in addition to the Afro-Americans and Ashkenazi Jews (Beutler et al. 1974), the Punjabis of the Indian subcontinent (this report) were found to exhibit the GPX1 polymorphism due to the GPX1 *2 allele. The data discussed in this paper (which included unpublished observations on several African and non-African populations) suggest that the GPX1 *2 allele is originally an African variant and hint that the present day Punjabis of Indian subcontinent, like Ashkenazi Jews, are "predominantly of Mediterranean origin with some proportion of African ancestry" ( Mourant et al. 1976).

A detailed procedure is described for a rapid detection of phosphoglucomutase-2(=phosphopentomutase;PGM-2) on Cellogel following electrophoresis of extracts of human red blood cells and other tissues, including cultured fibroblasts and various types of primate-rodent somatic hybrid cells. The present study indicated that there is only one locus for phosphopentomutase in man. The data from a selected panel of 20 independent clones of man-mouse somatic cell hybrids, investigated for the presence of human chromosomes and for the presence or absence of human PGM-2 favored the assignment of the human PGM-2 locus to chromosome 4.

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A simple chromogenic staining procedure is described for the specific identification of biliverdin reductase (BLVR)