Molecular spectrum of beta-thalassemia in the Mexican population.
Beta-thalassemia (beta-thal) is present in 59% and 75% of patients with abnormal hemoglobin disorders in northwestern and central Mexico, respectively. In our Research Center, up until 1997, we reported the presence of 13 beta-thal alleles in 26 unrelated chromosomes (-28A>C; -87C>T; MET1VAL; IVS1, G>A, +1; IVS1, G>A, +5; IVS1, G>C, +5; IVS1, G>A, +110; IVS2, C>G, +745; GLU6FS; VAL11FS; GLN39TER; HBD/HBB 104 kb del; and HBD87/HBB116 fusion). Since then, 57 more beta-thal chromosomes have been identified by the amplification-refractory mutation system (ARMS) and DNA sequencing from 54 individuals with beta-thalassemia (seven compound heterozygotes, three with two beta-thal alleles, three with beta-thal and HbS, and one with beta-thal and HbD; and 47 beta-thal heterozygotes). Nine of the previously observed alleles were found, together with three new alleles: IVS2, G>A, +1; LYS17TER; and 4-bp del, 41/42CTTT. Moreover, a novel mutation was observed, HIS77FS, bringing to a total of 17 beta-thal alleles identified in our population. Six alleles constitute 78.3% of the observed alleles: five Mediterranean alleles (GLN39TER; IVS1, G>A, +1; IVS1, G>A, +110; HBD/HBB 104 kb del; and IVS1, G>A, +5) and one common in the Kurdish population (-28A>C). We note especially the presence in these families of -28A>C and VAL11FS, both of which have previously been considered private alleles. The observed spectrum of mutations is characteristic of populations with low frequencies of thalassemias. Because thalassemia is not a rare disease in Mexico, we emphasize its necessary consideration in the differential diagnosis of microcytic hypochromic anemia.
División de Genética, Centro de Investigación Biomédica de Occidente, CMNO, IMSS, Guadalajara, Jalisco, Mexico.
F Javier
FJ
Perea
María Teresa
MT
Magaña
José G
JG
Cobián
J Yoaly
JY
Sánchez-López
María L
ML
Chávez
Guadalupe
G
Zamudio
María A
MA
Esparza
Beatriz
B
López-Guido
Bertha
B
Ibarra
D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D008800:Mexico; D014176:Protein Biosynthesis; D017086:beta-Thalassemia / Q000235:genetics*