[Identification of a focus of beta-thalassemia in Tamiahua, Veracruz].

The prevalence of beta thalassemia (B-thal) in Mexico is largely unknown, and it is thought that the disease is confined to populations with Mediterranean ancestors. Various reports suggest that in certain parts of the coast in the Gulf of Mexico the prevalence of both B-thal and hemoglobin S disease/trait is high. We studied prospectively a town with 11,000 inhabitants named Tamiahua, located along the Gulf Coast, in the State of Veracruz, and very close to the State of Tamaulipas. A group of 200 inhabitants was initially studied: the prevalence of B-thal was 15% and 6% of them had sickle cell trait. The prevalence of B-thal is the highest reported in the country. In a second part of the study, two family trees with members heterozygous for B-thal and/or Hb S trait were constructed. The ethnic characteristics of the studied population makes unlikely that the gene was derived from white Europeans but not from black Africans. Inasmuch as the indians living in that part of the country belong to the macro-maya glotochronological group, where a relatively high prevalence of B-thal has also been identified, we feel that it is possible that B-thal was present in our country before the Spaniards arrived to Mexico.