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Cystic fibrosis (CF) is an autosomal recessive disorder with an incidence of about 1/2,500 live births in European and other European-descended populations; this incidence corresponds to a carrier frequency of [...], The frequencies of the ΔF508 deletion, the most common cystic fibrosis mutation in Europeans and European-derived populations, and the XV2C and KM 19 restriction fragment length polymorphisms that are tightly linked to the CFTR locus vary among populations. To determine the distribution of these extragenic markers and of the ΔF508 mutation, we analyzed 326 chromosomes of individuals from two South American Indian populations, the Guarani and the Kaingang. The allele and haplotype frequencies differed greatly between the two populations as well as among Amerindians and normal European Brazilians and European Brazilian cystic fibrosis patients. The absence of the ΔF508 mutation and the B haplotype are in agreement with the hypothesis that the ΔF508 mutation occurred after the divergence of these two populations. This finding is useful for populations containing a large Amerindian component and helps us to understand the origins of the ΔF508 deletion, the most common cystic fibrosis mutation in Europeans and European-derived populations, as well as the different incidences of cystic fibrosis in continental groups. KEY WORDS: CYSTIC FIBROSIS, DNA POLYMORPHISM, SOUTH AMERICAN INDIANS, GUARANI, KAINGANG, BRAZIL, PUEBLO INDIANS, ZUNI INDIANS, ΔF508 MUTATION, CFTR, CFTR HAPLOTYPES.

The genetic variability of butyrylcholinesterase (BChE, EC 3.1.1.8) is determined by two autosomal nonlinked loci (BCHE and CHE2). The BCHE locus codifies for the enzyme structure (Arpagaus et al. 1990), [...], The genetic variability of butyrylcholinesterase, determined by the BCHE and CHE2 loci, was examined in nine Brazilian Indian groups. In addition, a search for the presence of the BCHE*F allele was also performed in eight other Brazilian Indian samples and in five ad-mixed (black-Indian-white) rural Amazonian communities previously studied for the CHE2 locus and the BCHE*A allele. In the Indian populations the frequency of the BCHE*F allele varied from 0 to 7.1% ± 3.4 and the frequency of the CHE2 C5+ phenotype ranged from 1.4% ± 1.4 to 45.9% ± 3.8. This study seems to be the first to report the presence of the BCHE*F allele in native Americans. The BCHE*A allele appeared in one Indian group (1.4% ± 1.0), and we suggest that its existence in this tribe and in other native Americans can be explained by gene flow from white populations. Gene flow may also be the reason for the occurrence of the BCHE*F allele in Brazilian Indians, whereas the CHE2*C5 + allele may have been present in the paleo-Indians. The distributions of both the BCHE*F allele and the CHE2 C5+ phenotype in Brazilian Indians seem to be the result of the action of random genetic drift. KEY WORDS: BUTYRYLCHOLINESTERASE, BRAZILIAN INDIANS, ADMIXED POPULATIONS, SERUM CHOLINESTERASE

Presents the polymorphism of TAP1, TAP2, LMP2 and LMP7 genes in the Kaingang and Guarani Amerindian tribes and the Caucasoid population of the Brazilian State of Panama. Concept of population genetics; Location of TAP and LMP genes in the major histocompatibility complex; Association between genetic variants and diseases.