ABSTRACT
INTRODUCTION: Alpha-thalassemia (α-thal) is a common monogenic disorder worldwide. In mixed ethnic populations, α-thal and beta-thalassemia (ß-thal) can be expected, sometimes giving complex phenotypes, which without molecular analysis are not easily explained. We performed the molecular identification of α- and ß-thal alleles in 51 Mexican patients with microcytosis, hypochromia, and normal or low levels of HbA2 . METHODS: Common deletional alleles (-α(3.7) , -α(4.2) , - -(SEA) , - -(MED) , - -(FIL) , - -(THAI) , -α(20.5) ) and α-triplication were studied by gap-PCR and nondeletional alleles (α(IVSI) ((-5nt)) , α2 (NcoI) , α1 (NcoI) ) by ARMS. ß-thal alleles Cd39 (C>T), IVS1:1 (G>A), IVS1:110 (G>A), and Spanish δß-thal were also investigated. DNA sequencing was performed on HBA2, HBA1, and HBB genes. Negative samples were subjected to MLPA. RESULTS: In 35 subjects, we identified the mutations, -α(3.7) , - -(SEA) , - -(FIL) , α(IVSI) ((-5nt)) , and ααα(anti3.7) and two novel deletion alleles - -(Mex1) (6.8-8.9 kb) and - -(Mex2) (77.6-135.7 kb). Four individuals also had a ß-thal allele (Cd39/IVS1:110). No α-thal alleles were observed in 16 subjects, but three had a ß-thal mutation Cd39, IVS1:110, and Spanish δß-thal. CONCLUSION: α-thal is relatively common in Mexican patients, the combination with ß-thal is sometimes unexpected, and this underlines the importance of performing molecular analysis for both α- and ß-genes defects in patients showing microcytic hypochromic anemia.