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.

Papel das alteraçöes cromossômicas na etiologia da esterilidade masculina / Role of chromosome changes in the etiology of male sterility

Anomalias cromossômicas no homem podem levar à esterilidade. O estudo citogenético de 40 pacientes com histórico de azoospermia ou oligospermia severa foi realizado visando estimar a freqüência de anomalias cromossômicas na etiologia da esterilidade primária e avaliar se esse exame deve ser recomendado como subsídio para o diagnóstico em nosso meio. A constituiçäo cromossômica normal 46,XY estava presente em 31 pacientes; quatro eram portadores de anomalias cromossômicas: cariótipo 47,XXY; 47,XYY; 45,XY,t (13q14q); homem XX; três apresentavam instabilidade cromossômica e dois a variante cromossômica Gp+. A etiologia da esterilidade primária foi determinada em 10% dos pacientes. Discutiu-se o papel das instabilidades cromossômicas e das variantes cromossômicas. O estudo citogenéticos revelou-se relevante como subsídio ao diagnóstico