Diagnóstico molecular da talassemia a+ (deleção -a3.7) em indivíduos com microcitose e/ou hipocromia atendidos no hemocentro dalton barbosa cunha em natal, rio grande do norte

Abstract

Alpha thalassemia, one of the most common monogenic disorders in the world, results from an imbalance in α-globin chain synthesis, being the -α3.7 deletion the most important. Together with beta thalassemia and iron deficiency, alpha thalassemia represents an important cause of microcytosis and hypochromia. In order to diagnose and evaluate the prevalence of alpha-thalassemia (-α3.7 deletion) in individuals with microcytosis and/ or hypochromia (MCV ≤ 82 fL and MCH ≤ 27 pg, respectively) were analyzed blood samples from 319 individuals referred to hematology outpatient clinic of Hemocentro Dalton Barbosa Cunha, Natal-RN. All peripheral blood samples were submitted to the following laboratorial analysis: erythrogram, hemoglobin electrophoresis on cellulose acetate strips at alkaline pH, measurement of hemoglobins A2 and Fetal and serum ferritin by chemiluminescent immunometric assay. DNA samples were extracted by commercial kit and the -α3.7 deletion was investigated by PCR. Among the 319 subjects studied, 105 (32,9%) presented α-thalassemia: 93 (29,1%) were heterozygous (-α3.7/αα) and 12 (3,8%), homozygous (-α3.7/-α3.7). Related to ethnic group, negroes showed the greatest prevalence of thalassemia (45,7%), followed by mulattoes (32,3%) and caucasian (29,1%). Alpha thalassemia was associated with other hemoglobinopathies in 13 (12,3%) patients with -α3.7 deletion, being 7,6% related to sickle cell trait, 1,9% to sickle cell disease and 2,8% related to beta thalassemia trait, showing the coexistence of these hemoglobin disorders in studied population. Of 105 patients diagnosed as alpha-thalassemia carrier, 9 (8,6%) had concomitant iron deficiency. Our data show the presence of -α3.7 deletion in our population and attest the importance of molecular diagnosis of alpha thalassemia to prevent erroneous and expensive investigations to define the etiology of microcytosis and hypochromia and unnecessary prolonged iron supplementation.