Frequency of Thalassemias in the Brazilian Population and Comparison Between Diagnostic Methods: A Systematic Review

Thalassemia is an inherited hemoglobin disorder caused by reduced or absent globin chain synthesis, with heterogeneous distribution worldwide and in Brazil. Back-ground/Objectives: This systematic review aimed to estimate the frequency of thalas-semia in the Brazilian population according to thalassemia type, geographic region, and population characteristics, as well as to evaluate the impact of diagnostic methods on frequency estimates. Methods: A systematic review was performed following PRISMA 2020 recommendations, in January 2026, including original studies conducted in Brazil-ian populations that reported thalassemia frequency data. Results: Thirty-six studies met the inclusion criteria, of which 77.8% were classified as high quality. The overall average frequency of thalassemia in Brazil was 7.5%, varying according to thalassemia type and diagnostic approach. The mean frequency of alpha thalassemia carriers was 12.3% (range: 5.5–54.0%), with regional variation from 5.79% in the Midwest to 17.3% in the Southeast. The −α3·7 kb deletion was the most frequently reported mutation na-tionwide. Beta thalassemia showed a mean frequency of 2.81% (range: 0.24–18.1%), with regional values ranging from 0.59% in the Southeast to 12.2% in the North and a wide spectrum of pathogenic variants. Distinct frequency patterns were observed in populations with inherent interpretative bias, including individuals with sickle cell trait, systemic lupus erythematosus, microcytosis, and Black populations. Molecular diagnostic methods demonstrated higher sensitivity, enabling the detection of asymp-tomatic carriers and reducing false-negative results. Conclusions: These findings pro-vide a comprehensive epidemiological overview of thalassemia in Brazil and reinforce the importance of molecular diagnostics for accurate screening, genetic counseling, and the development of public health strategies.