"Minor" hemoglobinopathies: a risk factor for asthma.

BACKGROUND: Thalassemia, sickle cell disease and other hemoglobinopathies are not rare in Portugal and European Mediterranean area. Homozygotic patients present major hematological disease but heterozygotic minor assymptomatic forms are frequent, mainly thalassemia minor and sickle cell trait. In these cases mycrocytosis with decrease or red cell volume and mean corpuscular volume or abnormal rigid erythrocytes are found and can lead to hemorheologic disturbances. The purpose of this study is to evaluate the incidence of asthma in hemoglobinopatic patients allergic to house dust mites.
METHOD: From 4.000 patients seen in the last 5 years in an out-patient allergy clinic, 63 cases of hemoglobinopathies have been confirmed by red cell count, hemoglobin electrophoresis, assays of hemoglobin A2, Fc, and S, and sickle cell test. All these patients had allergic disease characterized by clinical history, skin prick test to aeroallergens total and specific IgE (RAST-CAP-FEIA) and respiratory function evaluation.
RESULTS: 66 Hemoglobinopathies: Betathalassemia 61 cases, Betadelta thalassemia 2, sickle cell trait 2, Hemoglobin C, 1.57 patients have respiratory allergy, rhinitis in 14 cases of thalassemia and 1 of hemoglobin C, asthma with or without rhinitis in 41 cases of thalassemia and 1 case of sickle cell trait, the other 6 cutaneous allergy. Therefore asthma was present in 75.0% of the respiratory allergic patients and rhinitis only in 25.0%. In contrast in a control group of 491 respiratory allergic patients wihout hemoglobinopathies, 57% has asthma and 43% only rhinitis.
CONCLUSION: The prevalence of asthma is higher in thalassemia minor and sickle cell trait (p<0.05 Square chi test). Hemorheological changes probably a greater rigidity of red blood cells in capillary bed can contribute to changes in bronchial circulation and bronchial hypereactivity. Detection of hemoglobinopathies must be done in asthmatic patients with slight anemia or mycrocytosis.