Presence of allele alphaLELY in an Amazonian Indian population.
Allele alphaLELY is a low-expression allele of the erythroid spectrin alpha-chain that is characterized by a C --> G mutation at position alpha1857 in exon 40 and a C --> T (nt -12) mutation in intron 45. This second mutation is probably responsible for the partial skipping of exon 46. This exon is essential for the nucleation of the alpha-chains by the beta-chains during erythropoeisis. Although allele alphaLELY remains asymptomatic in both heterozygotes and homozygotes, it enhances the expression of deleterious alpha-alleles that occur and, as such, has clinical importance. In this study, the frequency of allele alphaLELY was estimated in two ethnically different Brazilian populations: a random sample of blood donors from Campinas, a city located in São Paulo State, in the southeastern region of Brazil, and a sample of Parakanã Indians (Tupi tribe), a very isolated population with a high degree of inbreeding. The frequency of allele alphaLELY in the blood donor's sample (n = 54) was 24.1% whereas in the indigenous sample (n = 41), it was 15.9%. These frequencies were not significantly different at the 5% level (chi2 = 1.931). Similarly, when the frequencies of our samples were compared with those of the four ethnic groups studied by Maréchal et al. [Br J Haematol 90:553-556, 1995], no significant differences were found at the 5% level (chi2 = 6.686). These results suggest that allele alphaLELY is a very ancient allele since it occurs with a relatively uniform and high frequency in all human ethnic groups studied so far. These findings confirm the importance of allele alphaLELY in influencing the expression of deleterious alpha-spectrin alleles. To our knowledge, these are the first data concerning allele alphaLELY in native Americans.
Bassères
D S
DS
Hemocentro, Universidade Estadual de Campinas, SP, Brazil.
Salles
T S
TS
Costa
F F
FF
Saad
S T
ST
D000483:Alleles; D044383:Black People / Q000235:genetics; D001938:Brazil / Q000208:ethnology; D004247:DNA / Q000032:analysis; D017931:DNA Primers / Q000737:chemistry; D005787:Gene Frequency; D006801:Humans; D007199:Indians, South American / Q000235:genetics*; D013049:Spectrin / Q000235:genetics*; D044465:White People / Q000235:genetics
D017931:DNA Primers; D013049:Spectrin; D004247:DNA