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

Fernanda Cozendey Anselmo; Abdou Gafar Soumanou; Cleidiane de Aguiar Ferreira; Flora Maia Viga Sobrinha; Ana Caroline Santos Castro; Rafael Oliveira Brito; Adolfo José da Mota; Marilda de Souza Gonçalves; José Pereira de Moura Neto

doi:10.4084/MJHID.2021.001

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

Mediterr J Hematol Infect Dis. 2021 Jan 1;13(1):e2021001. doi: 10.4084/MJHID.2021.001. eCollection 2021.

Affiliations

¹ Universidade do Estado do Amazonas - Fundação Hospitalar de Hematologia e Hemoterapia do Amazonas, Manaus, Amazonas, Brasil.
² Universidade Federal do Amazonas, Faculdade de Ciências Farmacêuticas, Manaus, Amazonas, Brasil.
³ Secretaria do Estado do Amazonas - SUSAM.
⁴ Fundação Oswaldo Cruz - Centro de Pesquisas Gonçalo Moniz, Salvador, Bahia, Brasil.

Abstract

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.

Keywords: Alpha Thalassemia; Amazonas; Brazil; Iron Treatment.