Document Type



PGM types were determined in 695 Whites and 1,032 Blacks from Porto Alegre, as well as in 38 Xikrin Indians of northern Brazil. Whites showed a higher prevalence of PGM21 than Blacks, the frequency of this marker being 0.26 among the Indians. No lack of heterozygotes was observed in this system, in disagreement with find­ings from two other reports. Two rare phenotypes were found, classified as PGM] 6-2 and PGM] 3-1. The Whites were all homozygotes for PGM12, its allele PGM22 showing a frequency of 0.01 among the Blacks and also occurring among the Indians, may be due to racial admixture. A “null” allele at this locus was also discovered as a result of an apparent maternity exclusion.