Population genetic study of red cell enzyme phosphoglucose isomerase in India

Abstract

SummaryThe distribution of red cell enzyme phosphoglucose isomerase was studied by starch gel electrophoresis in 27 different endogamous groups of India. Forty one electrophoretic variants belonging to four out of the nine known heterozygote types and one rare homozygous variant (PGI-3) were found. Comparison of the results with in India and certain other populations showed that PGI is certainly another useful genetic parameter for the study of population diversity in Asia.Inherited variation of the enzyme phosphoglucose isomerase [PGI; o~-D-glucose 6-phosphate ketol isomerase; EC 5.3.1.9] was initially described by Detter et al. (1968), the enzyme being referred to as phosphohexose isomerase. Since this discovery there have been reports of rare genetically determined variants or variants with low catalytic activities from various populations of the world Fitch et al., 1968;Paglia et al., 1969;Shinoda, 1970; Tariverdian et aI., 1970;Welch 1971;Luan Eng and Welch, 1972;Sanpitak et aL, 1973; Nakashima et aI., 1973;Isacchi et al., 1979), most of which concerns the sporadic occurrence of one or two of the nine heterozygotic types originally described in addition to the usual homozygous phenotype PGI-1. The exceptions are the heterozygous phenotypes PGI 3-1 and 4-1 which are of particular interest in Asiatic populations. In both the studies from London (Detter et al., 1968;Welch, 1971) the Asiatic Indians showed an appreciable frequency of the variant PGI 3-1 and subsequent studies of indigenous samples confirmed that the PGI a allele attains polymorphic frequencies in certain populations of India. Indeed, the relatively high frequency of this allele led to the detection of the homozygous phenotype PGI-3 (Papiha et aL, 1974). Ishimoto and Kuwata (1974) compiled the PGI studies in Japan and showed that in Japanese PGI 4-1 variant is more frequent than the other known heterozygous variants. This relatively high frequency of the PGI 4 allele in Japan consistent with the previous studies of Shinoda (1970), also led to the finding of a rare

Electrophoretic Variants of Red Cell Phosphoglucose Isomerase in Some Caste Populations of Punjab

“…This study adds new information on a further 640 samples, and thus the overall incidence of PGI 3-1 in Punjab comes out to be about I %. Similar observations were made by Papiha and Chahal [1984] regard ing all Indian populations. Unlike several other North Indian populations investi gated from Himachal Pradesh, Uttar Pra desh, Rajasthan and Delhi, in which var iants other than PGI3-1 have also been found, PGI 3-1 appears to be the only type present in the Punjab populations.…”

“…As for the Punjab populations, there are previous data on a total of 503 samples of which seven examples were PGI 3-1 and one PGI 3-3 [Papiha et al, 1972;Cha hal and Papiha, 1981;Papiha and Chahal, 1984]. This study adds new information on a further 640 samples, and thus the overall incidence of PGI 3-1 in Punjab comes out to be about I %.…”

“…A number of indigenous populations from different parts of India, both tribal and non-tribal, have now been screened for rare types of PGI [for review, see Pa piha and Chahal, 1984], and of the eight types described in the original study [Detter et al, 1968], six (PGI 2-1, 3-1, 5-1, 7-1, 8-1 and 9-1) have been found. It is interest ing to note that while PGI 3-1 is ubiqui tous in India and relatively more frequent, the occurrence of the other variants is only sporadic, albeit occasionally also showing some regional and ethnic affiliations.…”

“…The PGI isoenzymes were separated by horizontal starch gel electrophoresis essentially as described in Papiha and Chahal [1984], and staining was performed using a high-purity fructose-6-phosphate (disodium salt) preparation sup plied by Boehringer.…”

“…The triplet pattern suggests a dimeric structure for the enzyme. All these deviating phenotypes are rare in most hu man populations tested, except PGI 3-1 and 4-1, which have been observed with a frequency of about 1% in Asiatic Indians [Detter et al, 1968;Papiha and Chahal, 1984] and Japanese [Shinoda, 1970;Ishimoto and Kuwata, 1974], respectively.…”