Detection of Common Deletional of α-Thalassemia 3.7 Kb from Metropolitan Region of Manaus, Amazonas, Brazil

BACKGROUND: Alpha Thalassemia (α-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. The prevalence ranges from 20% and 35% in Brazil, depending mainly on race, predominant in Afro-descendants. PURPOSE: The aim was to determine α-thal -(α3.7Kb) and -(α4.2Kb) deletions, estimating their frequency in individuals from six regions of Amazonas State. METHODS: Volunteers age between 18–59 years old of both genders participated in the study. Blood was collected from March 2014 to September 2017 at the health centers of each participant city. α-thal(3.7Kb) was performed by GAP-PCR, while α-thal(4.2Kb) by Multiplex-PCR. The total samples collected from each city were: Manaus (capital), 356 (19.7%); 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. Microcytosis (MCV <80fL) was found in 158 individuals (8,46%) and α-thal diagnosed in 143 individuals (7.9%), and all of these individuals carried the (3.7Kb) deletion 5.95% in heterozygous and 1.95% in homozygous. α-thal(4.2kb) was not found in any volunteer. The association analyses to the α-thal(3.7kb) genotypes were statistically significant for all hematological parameters (p<.001), except serum iron and serum ferritin analyses. CONCLUSION: This study highlights α-thal 3.7kb deletion as an important public health problem, especially in a population not yet characterized about this disease. Thus, epidemiological studies using molecular tools become relevant in regions where the disease is underestimated, contributing to a better understanding of thalassemia incidence and iron deficiency anemias incidence of the participating cities. We reinforce that future molecular studies in North Region from Brazil can be utilized to describe other genetic anemias as structural hemoglobinopathies that have already proven to be highly prevalent in Brazil.