1B. Ibarra, 1,2M.T. Magaña, 1,2J.G. Cobián, 1,2Y.J. Sánchez-López, 1,2A.L. Camacho, 1M.L. Chávez, 1G. Zamudio, 1F.J. Perea
1División de Genética , Centro de Investigación Biomédica de Occidente, CMNO, IMSS, Sierra Mojada No. 800, Guadalajara, Jalisco, México, 2Doctorado en Genética Humana, Universidad de Guadalajara, Sierra Mojada No. 800, Guadalajara, Jalisco, México
Beta Thalassemia (beta-thal) is present in 67% and 76% of patients with abnormal hemoglobin disorders studied in Northwestern and Central Mexico respectively. In our Research Center until 1997 we reported the presence of 12 beta-thal alleles in 25 unrelated chromosomes, (-28A-C, -87C-G, MET1VAL, IVS1, G-A, +1, IVS1, G-A, +5, IVS1, G-C, +5, IVS1, G-A, +110, IVS2, C-G, +745, GLU6FS, VAL11FS, GLN39TER and HBD/HBB 104 DEL). Since then, 55 additional beta-thal chromosomes were identified by RFLP's, ARMS and DNA sequencing. 8 of the previously observed alleles were found plus 4 new ones IVS2, G-A, +1, LYS17TER, 4-BP DEL, 41/42CTTT and HBD87/HBB116 FUSION. Besides, a novel mutation was observed, HIS77FS, giving a total of 17 beta-thal alleles identified in our population. 6 alleles constitute 77.5% of the observed alleles, 5 Mediterranean (GLN39TER, IVS1, G-A +1, IVS1, G-A, +110, HBD/HBB 104 DEL and IVS1, G-A, +5) and one common in Kurdish population (-28A-C). We stress the presence of -28A-C and VAL11FS, in additional families, two previously considered as private alleles. The observed spectrum of the mutations is characteristic of the populations with low frequency of thalassemias. Since thalassemia is not a rare disease in Mexico, we stress the necessity to consider it in the differential diagnosis of hypochromic anemia.
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