Long-term follow up of patients with transcobalamin II deficiency.

Five cases of transcobalamin II deficiency presenting to our institution were reviewed. A delay in diagnosis often led to acute deterioration. Two patients have long term neurological sequelae. Minimal treatment in these patients may be dangerous. While haematological normality may be maintained, the adequate therapeutic dose of vitamin B-12 to allow normal neurological development and function is not easily determined and damage sustained early in life may be irreversible.