Genetic variants of serum butyrylcholinesterase in Chilean Mapuche Indians

Abstract

We estimated the frequencies of serum butyrylcholinesterase (BChE) alleles in three tribes of Mapuche Indians from southern Chile, using enzymatic methods, and we estimated the frequency of allele BCHE*K in one tribe using primer reduced restriction analysis (PCR-PIRA). The three tribes have different degrees of European admixture, which is reflected in the observed frequencies of the atypical allele BCHE*A: 1.11% in Huilliches, 0.89% in Cuncos, and 0% in Pehuenches. This result is evidence in favor of the hypothesis that BCHE*A is absent in native Amerindians. The frequencies of BCHE*F were higher than in most reported studies (3.89%, 5.78%, and 4.41%, respectively). These results are probably due to an overestimation of the frequency of allele BCHE*F, since none of the 20 BCHE UF individuals (by the enzymatic test) individuals analyzed showed either of the two DNA base substitutions associated with this allele. Although enzymatic methods rarely detect the presence of allele BCHE*K, PCR-PIRA found the allele in an appreciable frequency (5.76%), although lower than that found in other ethnic groups. Since observed frequencies of unusual alleles correspond to estimated percentages of European admixture, it is likely that none of these unusual alleles were present in Mapuche Indians before the arrival of Europeans.

Butyrylcholinesterase genetic variability in Guarani Amerindians from the Brazilian state of Mato Grosso do Sul

“…This was the first time Brazilian Amerindians have been screened for the A539T allele, which occurred with a similar frequency to that found by Acuña et al (2003) in the Chilean Mapuche (5.76% ± 2.29%; c 2 = 0.49, p > 0.45). The frequency of the A539T allele in the Guarani of Mato Grosso do Sul is significantly lower (p < 0.0001) than that found in Euro-Brazilians (18.4% ± 2.8%, c 2 = 41.19) and Afro-Brazilians (17.1% ± 2.9%, c 2 = 33.53) by Souza et al (1998) and is also lower (p < 0.001 at least) than in other non-isolated populations already studied, including populations from North America (12.8% ± 3.4%, c 2 = 11.49, Bartels et al, 1992b), Japan (16.4% ± 2.4%, c 2 = 35.31, Shibuta et al, 1994 and 17.5% ± 2.3%, c 2 = 42.62, Izumi et al, 1994), Denmark (18.0% ± 5.4%, c 2 = 16.60, Jensen et al, 1996) and Scotland (19.6% ± 3.9%, c 2 = 35.48, Gaffney and Campbell, 1994).…”

“…Considering that the A539T allele frequency is 17.80% in Euro-and Afro-Brazilians (Souza et al, 1998), the expected frequency due only to admixture for the A539T variant in this Guarani sample would be 1.38% and is statistically lower (c 2 = 19.14, p < 0.001) than the 3.69% found in the present study. The hypothesis that the A539T allele only occurred in Amerindians due to admixture was formulated by Acuña et al (2003) to explain the frequency of this variant in the Chilean Mapuche but the present data can only be explained by European admixture if it was followed by genetic drift. Considering that the A539T allele has a wide ethnical distribution and could also have been present in paleo-Amerindians, an alternative hypothesis is that the low frequency found in this Guarani group in relation to other ethnic groups could be due only to the role played by genetic drift in a small and isolated population.…”

“…Although the D70G allele has also been found in Mexican Amerindians at frequencies of 0.9% ± 0.4% (Lisker et al, 1964), 0.5% ± 0.1% (Lisker et al, 1967) and 3.8% ± 1.0% (Vergnes and Quilici, 1970) it was not found in the only two North-American groups so far studied, the Apache (Lubin et al, 1971) and the Navajo (Garry, 1977). Acuña et al (2003) reported the D70G allele frequencies in the Chilean Mapuche people: 1.1% ± 0.8% in the Huilliche; 0.9% ± 0.6% in the Cunco and 0.0% in the Pehuenche. The present data appear to be the first obtained for Amerindians at the DNA level, and show that the frequency of the D70G allele is within the range previously observed in the few Amerindian samples in which it has been found.…”

Polymorphisms of pesticide-metabolizing genes in children living in intensive farming communities

“…Similar frequencies have been observed in populations of different ethnic and geographic origins (Souza et al, 1998) and our results (0.19) are consistent with these studies. Other BCHE deficiency variants are uncommon, such as the dibucaine-resistant atypical variant (BCHE-A), with an allele frequency from 1.5% to 7.3% in European populations (Acuña et al, 2003;Jensen et al, 1995;Lockridge, 1992). The allele frequency observed in our study (2%) falls within this range.…”

Five new naturally occurring mutations of the BCHE gene and frequencies of 12 butyrylcholinesterase alleles in a Brazilian population

“…The high A539T allele frequency in Table 1 (1 out of 3 individuals presents this allele) does not differ statistically (w 2 ) from those previously found for Southern Brazil (18.4 ± 2.8% in a sample with European ancestry and 17.1 ± 2.9% in a sample with European and African admixture) [19], North America (12.8 ± 3.4%) [20], Scotland (19.6 ± 3.9%) [21], Denmark (18.0 ± 5.4%) [22] and Japan (16.4 ± 2.4% [23]; 17.5 ± 2.3% [24]). This polymorphic allele with a worldwide distribution was also found in Amerindians from South America with lower frequencies than in other ethnic groups: Mapuche from Chile (5.76 ± 2.29%) [25] and Guarani from the Brazilian State of Mato Grosso do Sul (3.69 ± 0.85%) [26]. This variant, however, was not found in samples of Georgian (N = 86) and Ashkenazi (N = 30) Jews in which the atypical allele (D70G) was found with frequencies of 5.8 and 3.3%, respectively [27].…”