Heterozygous beta-thalassemia: not infrequent in Mexico

The prevalence of beta-thalassemia in Mexico is not known in detail.

Data of studies investigating abnormal hemoglobins between September 1987 and November 2000 were analyzed; in addition, data of red-blood-cell indices and clinical features were analyzed in patients identified as carriers of beta-thalassemia.

In 1,639 prospective studies looking for abnormal hemoglobins, 429 disclosed some abnormality; of these, 319 cases displayed abnormally high levels of hemoglobin A2, thus consistent with the diagnosis of beta-thalassemia. This hemoglobin abnormality represented 74.2% of all abnormalities, both quantitative and qualitative, of the molecule of hemoglobin. There were 317 heterozygotes and only two homozygotes. We have previously shown that the most frequent cause of anemia as the iatrotropic condition in Mexican mestizos is iron deficiency. We found that iron deficiency is 11.5 times more frequent than beta-thalassemia and that the latter is 1.3 times more frequent than macrocytic/megaloblastic anemia.

beta-thalassemia should not be considered as infrequent in Mexico, and individuals with red blood cell microcytosis and/or hypochromia with or without anemia should be screened for thalassemia.