Novel Association between Flavin-Containing Monooxygenase 3 Gene Polymorphism and Antithyroid Drug-Induced Agranulocytosis in the Han Population

Some effective antithyroid drugs (ATDs) have been widely used for patients with Graves' disease (GD) but are associated with ATD-induced agranulocytosis. We selected 29 ATD-induced agranulocytosis patients, 44 ATD-induced neutropenia patients, and 140 GD controls among the -Chinese Han population who were recruited at the First Affiliated Hospital of Xi'an Jiao Tong University. We assessed their response to ATDs treatment by performing genotyping for a candidate gene association study of samples from patients receiving treatment. Human flavin-containing monooxygenase 3 (FMO3), which is the major hepatic enzyme involved in the production of N-oxide of trimethylamine, catalyzes the oxygenation of a variety of drug compounds. Six single SNP, genotype, haplotype (HAP), and association analyses of the FMO3 gene with ATD-induced agranulocytosis/neutropenia under different models (i.e., additive, dominant, and recessive models) were performed. Rs1736557, which caused an amino acid variation V257M, showed a strong association between ATD-induced agranulocytosis and GD controls after Bonferroni correction (p = 0.011, OR 2.301, 95% CI 1.201-4.409). The presence of HAP 3 (HAP3) in the FMO3 gene HAP was statistically associated with ATD-induced agranulocytosis (p = 0.038, permutation p value). Our findings indicate that genetic variations in the FMO3 gene are associated with the response to ATDs maintenance treatment in ATD-induced agranulocytosis patients of -Chinese Han population. (c) 2019 S. Karger AG, Basel