Abstract Background Thiamine-responsive megaloblastic anemia syndrome represents a rare autosomal recessive condition originating from mutations in the SLC19A2 gene. It is characterized by a classical triad of megaloblastic anemia, insulin-dependent diabetes mellitus, and sensorineural hearing loss. We present the case of a woman diagnosed with thiamine-responsive megaloblastic anemia, with no history of consanguinity, in whom genetic testing revealed novel SLC19A2 mutations and an unreported clinical manifestation. Case Presentation This case describes an 18-year-old mestizo female patient who presented with a medical history of diabetes starting in infancy, bilateral sensorineural hearing loss, and megaloblastic anemia. The diagnosis of thiamine-responsive megaloblastic anemia was confirmed by genetic testing, which detected compound heterozygous mutations in the SLC19A2 gene that included a pathogenic frameshift mutation (c. 620₆24dup; p. Pro209Phefs*21) and a missense variant (c. 170 T > C; p. Leu57Pro). The patient also experienced thrombotic events, including deep vein and mesenteric thrombosis, previously unreported findings in thiamine-responsive megaloblastic anemia. High-dose thiamine treatment resulted in improved hematologic and glycemic control. Conclusion This case broadens the genetic and clinical spectrum of thiamine-responsive megaloblastic anemia, highlighting the importance of genetic testing in young patients with the classic triad and showing that early thiamine therapy can markedly improve outcomes.
Jiménez et al. (Mon,) studied this question.