HAPLOTYPE ANALYSIS AND (A)GAMMA GENE POLYMORPHISM ASSOCIATED WITH THEBRAZILIAN TYPE OF HEREDITARY PERSISTENCE OF FETAL HEMOGLOBIN

We have identified three unrelated individuals and three members of a family with the non-deletion form of (A) gamma-hereditary persistence of fetal hemoglobin (HPFH). Molecular analysis showed that each indivi dual is a heterozygote for a previously described -195 (A) gamma (C--> G) mutation. The beta-globin gene cluster was studied using the polyme rase chain reaction and related techniques. Haplotyping using nine res triction sites identified two closely related chromosomes with the -19 5 (A) gamma mutation, differing only in a single site 3' to the beta-g lobin gene. Further analysis of beta-globin framework indicated that t he HPFH allele segregates with haplotype V, according to Orkin's class ification. The second haplotype probably originated by a point mutatio n or DNA rearrangement of a pre-existing -195(A) gamma chromosome. We also determined the sequences from -622 to +55 bp upstream to the (A) gamma gene and part of the A(gamma) IVS-2. We found four polymorphisms associated to the -195(A) gamma promoter region. All -195(A) gamma ch romosomes had a G at positions -588 and +25 relative to the (A) gamma gene. One individual was also homozygous for polymorphisms at -398 (G- ->A), and another at -369 (C-->G). Cloning and sequencing of the polym orphic patterns of the 3' region of (A) gamma IVS-2 Showed that the mu tated allele is linked to beta-globin chromosome a, Some correlations between chromosome characteristics and (A) gamma point mutations were also observed, (C) 1998 Wiley-Liss, Inc.