Beta-thalassemia and beta[A] globin gene haplotypes in Mexican mestizos.
B-globin haplotypes of 20 beta-thalassemia (beta-thal) and 87 beta(A) Mexican mestizo chromosomes were analyzed to ascertain the origin of the beta-thal alleles and the frequencies and distribution of the beta(A) haplotypes among northwestern Mexican mestizos. Sixteen beta-thal chromosomes carried six Mediterranean alleles [five codon 39 C-->T; two IVS1:1 G-->A; two IVS1:5 G-->A; three IVS1:110 G(A; one codon 11 (-T) and three (deltabeta)zero-thal]; the remaining four were linked to three rare alleles (two -28 A-->C and one each: -87 C-->T and initiation codon ATG-->GTG). Among the 87 beta(A) chromosomes, 17 different 5' haplotypes with frequencies for 1, 3, 2 and 5 of 39.0%, 17. 2%, 9.2% and 6.9%, respectively, were observed. The beta-haplotype analysis showed that 13 out of 16 Mediterranean chromosomes could easily be explained by gene migration; however, one codon 39 associated with haplotype 4 (----+ +-), one IVS1:1 with haplotype 1(+----++) and one IVS1:5 G-->A, may represent separate mutational events. Analysis of the rare alleles showed that the -28 A-->C mutation was associated with the commonest beta(A) haplotype in Mexican mestizos, Mediterraneans and the total world population; therefore an independent origin cannot be ruled out. The -87 C-->T and initiation codon ATG-->GTG were found with beta-haplotypes different from the reported ones, suggesting an indigenous origin.
Villalobos-Arámbula
A R
AR
División de Genética, Centro de Investigacion Biomédica de Occidente,IMSS, Guadalajara, Jal., Mexico.
Bustos
R
R
Casas-Castañeda
M
M
Gutiérrez
E
E
Perea
F J
FJ
Thein
S L
SL
Ibarra
B
B
D000483:Alleles; D005787:Gene Frequency; D005914:Globins / Q000235:genetics*; D006239:Haplotypes; D006801:Humans; D007198:Indians, North American / Q000235:genetics*; D008800:Mexico; D009154:Mutation; D044465:White People / Q000235:genetics*; D017086:beta-Thalassemia / Q000235:genetics*
D005914:Globins