Cytochrome P4501A1 polymorphisms in South American Indians.

A total of 131 individuals from five Brazilian Indian tribes were studied for two CYP1A1 gene polymorphisms. The presence of the *val allele at codon 462 varied from 54% in the Surui to 97% in the Xavante, while the presence of the MspI restriction site (*m2 allele) at position T6235C ranged from 72% in the Gavião to 95% in the Xavante. The haplotypes derived from these two sites showed a highly heterogeneous distribution among the five populations. The most common haplotype in South Amerindians was *val/*m2 (54% to 94%). This prevalence is the highest that has been observed in any world population.