[Most frequent beta-thalassemia mutations in the Argentinian population].

PURPOSE: Identification of the beta-thalassemic alleles of higher incidence in our populations.

PATIENTS AND

METHODS

A total of 10 families (40 subjects) were analyzed. All families consisted of one son affected by beta-thalassaemia major (10 patients) and their parents and brothers (30 subjects). Genomic DNA was extracted from peripheral blood; a segment of 536 base pairs of the human beta-globin gene was selectively amplified with oligonucleotide primers by polymerase chain reaction (PCR) and the mutations in nucleotides 1 (IVS 1-1), 6 (IVS 1-6) and 110 (IVS 1-110) of intron 1 and codon 39 of exon 2 were analyzed by hybridization with allele-specific oligonucleotide probes (ASO).

RESULTS

The distribution of 20 mutated alleles of the patients was: IVS 1-1: 10%; IVS 1-6: 10%; IVS 1-110: 40%; codon 39: 30%; 2 unidentified alleles (10%) which could not be determined with the probes used in this study; 23 carriers and 1 subject with the two normal alleles, have been detected in the genetically related 30 subject population; the distribution of mutated alleles was similar to the patient with variations due to the number of children in each family.

CONCLUSIONS

1) in the analyzed population the most frequent mutations were IVS 1-110 and codon 39. -2) the diversity of beta-thalassemic alleles, together with their distribution (90% of 4 mutations), are similar to the results found in the Mediterranean area. -3) the compound genotype present in 70% of the patients is characteristic of a nonendogamic society. -4) the small number of brothers with 2 normal alleles, was noteworthy.