Transcobalamin II (TCII) is a primary plasma protein that binds vitamin B12 and facilitates its cellular uptake by many tissues.1 Inherited deficiency of TCII is a rare autosomal recessive disorder that results in severe megaloblastic anemia in early infancy despite normal serum vitamin B12 levels.
A 48-year-old man with congenital TCII deficiency has been under the care of our ophthalmology department for 19 years. He was born to nonconsanguineous parents. At age 9 days he was treated with repeated blood transfusions, vitamin B12 supplements, and folic acid supplements for megaloblastic anemia, vomiting, diarrhea, and bleeding. At age 24 months his delayed walking and unsteady gait responded well to vitamin B12 intramuscular injections. At age 30 months he developed epilepsy, which was treated with sodium valproate and phenobarbital.
Dharmasena A, Calcagni A, Kerr AR. Retinopathy in Inherited Transcobalamin II Deficiency. Arch Ophthalmol. 2008;126(1):141-142. doi:10.1001/archophthalmol.2007.21