What is thiamine-responsive megaloblastic anemia syndrome (TRMA) and how is it diagnosed?

Updated: Feb 18, 2019
  • Author: Srikanth Nagalla, MD, MS, FACP; Chief Editor: Emmanuel C Besa, MD  more...
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Thiamine-responsive megaloblastic anemia syndrome (TRMA) is an autosomal recessive disorder characterized by megaloblastic anemia, progressive sensorineural hearing loss, and diabetes mellitus. Onset of megaloblastic anemia occurs between infancy and adolescence. Vitamin B-12 and folic acid levels are normal. On bone marrow examination, affected individuals have megaloblastic changes with erythroblasts often containing iron-filled mitochondria (ringed sideroblasts). Molecular genetic testing will show biallelic pathogenic variants in SLC19A2. [13]  

Uncommonly, variable ocular anomalies may be present in TRMA. One case report describes symmetric bull's eye maculopathy and other ocular findings consistent with cone-rod degeneration. [14]

The anemia in TRMA is corrected with pharmacologic doses (50-100 mg/day) of thiamine (vitamin B1) . However, the red cells remain macrocytic. [13]

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