Treatment of tuberculosis (TB) can result in Drug-Induced Liver Injury (DILI) since hepatotoxic metabolites are formed during the biotransformation of isoniazid (INH). DILI can be related to the genetic profile of the patient. Single nucleotide polymorphisms in the CYP2E1 gene and GSTM1 and GSTT1 deletion polymorphisms have been associated with adverse events caused by INH. To characterize the genetic polymorphisms of CYP2E1, GSTT1 and GSTM1 in TB carriers. This is an observational prospective cohort study of 45 patients undergoing treatment of TB. PCR-RFLP and multiplex-PCR were used. The distribution of genotypic frequency in the promoter region (CYP2E1 gene) was: 98% wild genotype and 2% heterozygous. Intronic region: 78% wild genotype; 20% heterozygous and 2% homozygous variant. GST enzyme genes: 24% Null GSTM1 and 22% Null GSTT1. Patients with any variant allele of the CYP2E1 gene were grouped in the statistical analyses. Patients with the CYP2E1 variant genotype or Null GSTT1 showed higher risk of presenting DILI (p=0.09; OR: 4.57; 95% CI: 0.75-27.6). Individuals with both genotypes had no increased risk compared to individuals with one genotype.

Thalassemia, an autosomal recessive genetic disorder affecting production of normal globin chains, presents varying prevalence worldwide. The frequency of global α-thalassemia remains understudied, especially in Brazil, due to its genetic diversity and large population size. This study compared α-thalassemia frequency between microcytic patients and healthy volunteers in Rio de Janeiro, stratified by self-reported skin color. DNA extracted from whole blood/EDTA underwent genotyping for α-thalassemia using multiplex PCR, targeting α3.7 kb, α4.2 kb, αSEA, αMED, αFIL, and α20.5 kb deletions. Frequency of α-thalassemia among patients was 63.6%, distributed as follows: 62.1% for α3.7 kb deletion, 0.7% for α4.2 kb deletion, and 0.8% for αSEA deletion. In healthy volunteers, the prevalence was 3.2%, distributed as 0.53% in self-declared white, 1.07% in brown, and 1.60% in black individuals, all presenting heterozygous genotype for α3.7 kb deletion. Frequency in healthy population was significantly lower than that observed in microcytosis population (p < 0.001). Determining α-thalassemia frequency in highly admixed population may enhance genetic counseling, given that asymptomatic carriers can produce offspring with combinations of Hb variants, potentially leading to severe clinical phenotypes.

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 −α^{3.7 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.