Background and Aim: Thalassemia is one of the most common worldwide single-gene diseases. On the molecular level, it is a heterogeneous disease. So far, beside large deletions, more than fifty point mutations have been identified for this disease around the world. Four to ten percent of Iranians are carriers of thalassemia-affected genes. In this study we determined the relationship between the value of MCV/MCH and the type and severity of mutations in alpha thalassemia carriers.

Methods and Materials: The major abnormality in alpha thalassemia carriers is decreased values of MCV and MCH. A total of 104 adult alpha thalassemia heterozygotes, 20-40 years old, including 33 persons from Khoozestan Province and 71 from Khorasan Province, were included in the study. Two hundred and eight chromosomes were isolated from peripheral blood leukocytes using standard procedures. DNA samples were amplified by Gap-PCR.

Results: Only one ° mutation (MED) was found in 2.9% of the population. The carriers of this mutation had virtually identical ranges of MCV and MCH. In contrast, + mutations were associated with significant differences in mean MCV and MCH values. The various mean MCV/MCH ratios of ° carriers were statistically significantly lower than those of + heterozygote. The results indicated that the degree of reduction in MCV and MCH is directly related to the severity of the mutations. Deviations, in cases, were associated with lower numbers of the carriers.

Conclusion: Only one ° mutation (MED) was found in 2.9% of the population. The carriers of this mutation had virtually identical ranges of MCV and MCH. In contrast, + mutations were associated with significant differences in mean MCV and MCH values. The various mean MCV/MCH ratios of ° carriers were statistically significantly lower than those of + heterozygote. The results indicated that the degree of reduction in MCV and MCH is directly related to the severity of the mutations. Deviations, in cases, were associated with lower numbers of the carriers.