[Association of alpha and beta thalassemia with alpha gene triplication in one family].

UNLABELLED: We describe the haematological data and molecular results of a native family from Cádiz in that one is produced the a within heterozygous beta 0 thalassaemia (IVS-1, nt 1-G-->A), heterozygous alpha+ thalassaemia (-alpha 3.7) and alpha gene triplication (alpha alpha alpha 3.7). PATIENTS AND METHODS) We are studied 7 members to a family composed by father (I1), mother (I2) and five children (II1, II2, II3, II4, II5). The molecular biology study of the alpha gene was realized by Southern blot method using the restriction enzymes Bam HI, Bgl II and Eco RI and hybridized with alpha probe of the plasmid PRB 1 (fragment of 1.5 Kb digested with the enzyme Pst I). The genes were studied by the technique of the polymerase chain reaction (PCR), modified according to designated method "Amplification Refractory Mutation System" (ARMS).

RESULTS

The father (I1) presents an interaction of therozygous beta 0 thalassaemia with heterozygous alpha + thalassaemia (beta 0/beta 1;alpha alpha/-alpha 3). The mother (I2) shows an alpha gene triplication (beta A/beta A: alpha alpha alpha 3.7/alpha alpha). Finally the children are expressed 5 possibilities: II4 he is normal (beta A/beta A; alpha alpha/alpha alpha), II2 he has alpha gene triplication (beta A/beta A; alpha alpha/alpha alpha alpha 3.7), II3 he has heterozygous beta 0 thalassaemia (beta 0/beta A; alpha alpha/alpha alpha), II5 he has interaction between heterozygous beta 0 thalassaemia and heterozygous alpha gene triplication (beta 0/beta A; alpha alpha alpha 3.7/alpha alpha) and II1 presents an interaction between a heterozygous beta 0 thalassaemia and together with the lost of one alpha gene in one chromosome he also presents a alpha gene triplication in other one (beta o/beta A; alpha alpha/alpha alpha). The hematological data of II5 corresponds to a intermediate thalassemia with not transfusion dependent feature an opposite to II1 that presents a heterozygous thalassemic trait features with 4 alpha genes.

DISCUSSION: The phenotypical expression of the different interactions of these mutations in this family, points out, the relevant role that the unbalance globins chains plays in the pathogenesis and development of the clinical manifestations of the patients with the thalassaemia syndromes.