Allele alpha(LELY) is a low-expression allele of the erythroid spectrin alpha-chain that is characterized by a C --> G mutation at position alpha 1857 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 alpha(LELY) 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 alpha(LELY) was estimated in two ethnically different Brazilian populations: a random sample of blood donors from Campinas, a city located in Sao Paulo State, in the southeastern region of Brazil, and a sample of Parakana Indians (Tupi tribe), a very isolated population with a high degree of inbreeding. The frequency of allele alpha(LELY) 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 (chi(2) = 1.931). Similarly, when the frequencies of our samples were compared with those of the four ethnic groups studied by Marechal et al, [Br J Haematol 90:553-556, 1995], no significant differences were found at the 5% level (chi(2) = 6.686). These results suggest that allele alpha(LELY) 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 alpha(LELY) in influencing the expression of deleterious alpha-spectrin alleles. To our knowledge, these are the first data concerning allele alpha(LELY) in native Americans. (C) 1998 Wiley Liss, Inc.573212214