Thiamine-responsive megaloblastic anemia syndrome

Thiamine-responsive megaloblastic anemia syndrome (TRMA) is a rare condition that is characterized by hearing loss, diabetes, and a blood disorder called megaloblastic anemia. Megaloblastic anemia occurs when a person has a low number of red blood cells (anemia), and the red blood cells that are present are larger than normal (megaloblastic). The symptoms of this blood disorder may include decreased appetite, lack of energy, headaches, pale skin, diarrhea, and tingling or numbness in the hands and feet. Individuals with TRMA typically develop megaloblastic anemia between infancy and adolescence. TRMA is called "thiamine-responsive" because the anemia can be treated with daily doses of vitamin B1 (thiamine).

In people with TRMA, hearing loss typically develops during early childhood and is caused by abnormalities of the inner ear (sensorineural hearing loss). The hearing loss usually worsens over time. It remains unclear whether treatment with thiamine can improve hearing or delay hearing loss in people with TRMA.

People with TRMA often develop diabetes mellitus, a condition in which glucose levels can become dangerously high, at an early age. Although some individuals with TRMA develop diabetes during childhood, they do not have the autoimmune form of diabetes that typically develops in children, called type 1 diabetes. People with TRMA usually require insulin to treat their diabetes. In some cases, treatment with thiamine may delay the onset of diabetes or reduce the amount of insulin a person needs.

Some individuals with TRMA have abnormalities of the eye, including optic atrophy, which is the degeneration (atrophy) of the nerves that carry information from the eyes to the brain. Additional features of this condition may include heart and blood vessel (cardiovascular) problems, intellectual disabilities, behavioral changes, and seizures.