Ethnicity and glutathione S-transferase (GSTM1/GSTT1) polymorphisms in a Brazilian population

The distribution of polymorphisms related to glutathione S-transferases (GST) has been described in different populations, mainly for white individuals. We evaluated the distribution of GST mu (GSTM1) and theta (GSTT1) genotypes in 594 individuals, by multiplex PCR-based methods, using amplification of the exon 7 of CYP1A1 gene as an internal control. In São Paulo, 233 whites, 87 mulattos, and 137 blacks, all healthy blood-donor volunteers, were tested. In Bahia, where black and mulatto populations are more numerous, 137 subjects were evaluated. The frequency of the GSTM1 null genotype was significantly higher among whites (55.4 percent) than among mulattos (41.4 percent; P = 0.03) and blacks (32.8 percent; P < 0.0001) from São Paulo, or Bahian subjects in general (35.7 percent; P = 0.0003). There was no statistically different distribution among any non-white groups. The distribution of GSTT1 null genotype among groups did not differ significantly. The agreement between self-reported and interviewer classification of skin color in the Bahian group was low. The interviewer classification indicated a gradient of distribution of the GSTM1 null genotype from whites (55.6 percent) to light mulattos (40.4 percent), dark mulattos (32.0 percent) and blacks (28.6 percent). However, any information about race or ethnicity should be considered with caution regarding the bias introduced by different data collection techniques, specially in countries where racial admixture is intense, and ethnic definition boundaries are loose. Because homozygous deletions of GST gene might be associated with cancer risk, a better understanding of chemical metabolizing gene distribution can contribute to risk assessment of humans exposed to environmental carcinogens.

Utilization of citogenetic technics in paternity investigation

Th joint analysis of several genetic markers in casesof paternity investigation renders possible a cumulative probability of 99.7% of change of esclusion of a flasely accused father. The role of heteromorphism of the Y chromosome size was appraised in this work, with more than one genetic marker, in 20 expertise examinations in paternity investigation, where the children were male. The results found with found with this method, in association with the research on erythrocytic and leucocytic antigens showed the exclusion of two falsely accused men. Cytogenetic analysis with Giemsa stain in combination with leukocyte (HLA system) and erithrocyte antigens investigation demonstrated the exclusion of two men falsely accused