a talasemia no deleción en Espa？a: índices hematológicos anormales y su estudio molecular

the a thalassaemia diseases in most cases are caused by deletions that affect one or two of the a genes, being less frequent the cases due to punctual mutations, insertions or deletions of a few pairs of bases, which have been denominated no deletion a thalassaemias. the objective of this investigation was to determine the incidence of the no deletion a thalassaemia in patients with a thalassaemia using molecular biology techniques. we studied 517 individuals of the san carlos hospital (thalassemia molecular research center, madrid-spain) between january 2001 and december 2003, in whom iron deficiency anemia had been ruled out, that presented microcytosis and hypochromia and that presented normal hba2, hbf and eef from normal hbs. the two types of no deletion a thalassaemia most frequently described in the mediterranean were studied: 1) a hph due to deletion of 5bp in the ivs i and 2) anco due to a change in the initiation codon of the gene. of the 517 cases studied, 40 (7.7% of the cases) represented a no deletion a thalassaemia. of these cases, 28 were positive for ahph of the a2 gene, 24 in the heterozygote state, one homozygote and three double heterozygotes associated with the 3,7 kb deletion. the remaining 12 cases were positive for the anco of the a2 gene, 10 heterozygotes, one homozygote and one double heterozygote associated with the 4,2 kb deletion. the no deletion a thalassaemias represent < 8% from the cases in our environment. the ahph is the most frequent type of no deletion a thalassaemia and its haematological abnormalities are more manifest that the ones present in the cases of anco