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[Most frequent beta-thalassemia mutations in the Argentinian population]
V Varela1, S Abreu, L C Rossetti
1Cátedra de Genética y Biología Molecular, Facultad de Farmacia, Hospital de Clíncas José de San Martín, Universidad de Buenos Aires, Argentina.
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.