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Background: Alpha Thalassemia (a-thal) is a heterogeneous group of hereditary alterations caused by deletions that affect alpha regulatory genes and the 3.7Kb deletion is the most frequent worldwide. In Brazil, the prevalence ranges from 20% and 35%, depending mainly on race, being more predominant in Afro-descendants. Purpose: The aim was to determine ?-thal -?3.7Kb and -?4.2Kb deletions, estimating their frequency in individuals from five regions of Amazon. Methods: Volunteers (individuals >18 years old, of both genders) blood samples (n=1809) were collected from march 2014 to september 2017, at hospitals and/or health centers of each participant city. Alpha Thalassemia 3.7Kb genotyping was performed by GAP-PCR, while 4.2Kb deletion by Multiplex-PCR. The studied population included: Manaus (capital), 356 (19.7%) samples; Iranduba 232 (12.8%); Manacapuru, 287 (15.9%); Presidente Figueiredo, 370 (20.5%); Itacoatiara, 301 (16.6%); and Coari, 263 (14.5%). Results: The average age among males was 35.3±14.8, while for females it was 36.7±14.9 years old. Alpha Thalassemia was diagnosed in 143 individuals (7.9%) and all of these individuals carried the 3.7Kb deletion, 5.95% in heterozygosis and 1.95% in homozygosis. The associations analyses to the a-thal genotypes were statistically significant for all hematological parameters (p<.001), except serum iron and serum ferritin analyses among carriers ?-thal. Microcytosis (MCV <80fL) was found in 158 individuals (8,46%). Conclusion: The alfa-thal prevalence corroborates with other Brazilians studies. Molecular diagnosis is important to prevent the most severe forms of the disease, thus epidemiological studies using molecular tools become extremely important in regions where the disease is underestimated. In this context, this is the first study that reports ?-thalassemia deletion in the population from State of Amazonas. Our findings are relevant because they have impact in the clinical therapeutic choice and also demonstrate the importance of differential diagnosis between genetic anemia and iron deficiency anemia.
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