Novel Mutation in the SLC19A2 Gene in an Iranian Family with Thiamine-Responsive Megaloblastic Anemia: A Series of Three Cases

Thiamine-responsive megaloblastic anemia (TRMA) is a clinical triad characterized by megaloblastic anemia, non-autoimmune diabetes mellitus, and sensory-neural hearing loss. Mutations in the thiamine transporter gene, solute carrier family 19, member 2 (SLC19A2), have been associated with TRMA. Three pediatric patients from a large consanguineous Iranian family with hyperglycemia, anemia, and hearing loss were clinically diagnosed with TRMA. In all three patients, TRMA was confirmed by direct sequencing of the SLC19A2 gene that revealed a novel missense homozygous mutation c.382 G>A (p.E128K). This mutation results in the substitution of glutamic acid to lysine at position 128 in exon 2 and was not detected in 200 control chromosomes. Thiamine therapy reversed the anemia and alleviated the hyperglycemia in all three patients. We recommend sequence analysis of the SLC19A2 gene in individuals with a clinical triad of diabetes mellitus, hearing loss, and anemia. The administration of thiamine ameliorates the megaloblastic anemia and the hyperglycemia in patients with TRMA.