Correlation of beta-thalassemia mutations with alpha-thalassemia: an experience of the southwestern region of Iran.

BACKGROUND AND AIMS

Thalassemias are the commonest monogenic diseases worldwide. Mutations in genes coding for the globin proteins that alter protein output, produce the thalassemia syndromes. This study aimed to present the cases of alpha-thalassemia in beta-thalassemic patients from Khuzestan province in Iran.

MATERIALS AND METHODS

A total of 227 subjects (10-45 years, mean age of 14·8 years) including thalassemia patients (n=43), and their parents and siblings (n=184) from unrelated Khuzestani families were included in this study. The standard diagnostic marker for beta-thalassemia is elevation of the hemoglobin A2 (HbA2) level (>3·5%), while low mean corpuscular volume (MCV<80) and mean cell hemoglobin (MCH<27) with a normal HbA2 level indicate alpha-thalassemia carrier.

RESULTS

The amplification refractory mutation system polymerase chain reaction confirmed that among 227 subjects, 147 (64·75%) were heterozygous beta-thalassemia patients and 80 (35·25%) were identified either normal or with unknown mutations. Out of these 147 patients, nine cases were diagnosed as compound heterozygous. The IVS11-1(G-C) mutation was found in majority of chromosomes (40·08%). Out of nine beta/alpha-thalassemia patients, four showed -α(3·7)/αα (1·76%), two had -α(3·7)/-α(3·7) (0·88%), one had -α(4·2)/αα (0·44%) and one had - -MED/αα (0·44%) genotypes.

CONCLUSION

The present study suggests the need to establish a program for genetic counseling and prenatal diagnosis of beta-thalassemia for affected families and for initiating a control program by prospective screening of pregnant women. The application of the knowledge about mutation pattern was found to be beneficial since the mutations could be screened in the order in which they are present in our population. Hence, it will not only help to reduce the screening cost but also to promote early genetic counseling and prevention of an affected child.