RESUMO
BACKGROUND: The elevation of hemoglobin A2 (HbA2) is an essential criterion in the diagnosis of minor ss thalassemia. AIM: To report a case of minor ss thalassemia HbA2 with normal HbA2 rate. OBSERVATION: We report the case of ten years old boy, with hypochromic microcytic anemia, refractory to iron treatment. The study of hemoglobin (Hb) has revealed the presence of a minor abnormal fraction of Hb, amounted to 2.8%, associated with the presence of HbF and normal levels of HbA2. Family study revealed the presence of two Hb abnormalities (ss thalassemia trait and HbA2 mutant) transmitted to offspring in isolation or associated. The genotypic study confirmed the presence of minor, 0 thalassemia and a °/00 gene mutation, causing a new mutant HbA2 named HbA2 Pasteur-Tunis [°/00 59(E3)LysgAsn(AAGgAAC)]. CONCLUSION: The presence of °/00 mutant reduces HbA2 level and could hide ss thalassemia trait. Rigorous and methodical interpretation of phenotypic data is crucial to not overlook the presence of ss thalassemia trait, whose diagnosis is crucial for genetic counseling and prenatal diagnosis.
