Long-term outcome of a patient with Transcobalamin deficiency caused by the homozygous c.1115_1116delCA mutation in TCN2 gene: a case report

摘要

Transcobalamin deficiency is a rare autosomal recessive inborn error of cobalamin transport (prevalence: ?1/1000000) which clinically manifests in early infancy. We describe the case of a 31?years old woman who at the age of 30?days presented with the classical clinical and laboratory signs of an inborn error of vitamin B12 metabolism. Family history revealed a sister who died at the age of 3?months with a similar clinical syndrome and with pancytopenia. She was started on empirical intramuscular (IM) cobalamin supplements (injections of hydroxocobalamin 1?mg/day for 1?week and then 1?mg twice a week) and several transfusions of washed and concentrated red blood cells. With these treatments a clear improvement in symptoms was observed, with the disappearance of vomiting, diarrhea and normalization of the full blood count. At 8?years of age injections were stopped for about two and a half months causing the appearance of pancytopenia. IM hydroxocobalamin was then restarted sine die. The definitive diagnosis could only be established at 29?years of age when a genetic evaluation revealed the homozygous c.1115_1116delCA mutation of TCN2 gene (p.Q373GfsX38). Currently she is healthy and she is taking 1?mg of IM hydroxocobalamin once a week. Our case report highlights that early detection of TC deficiency and early initiation of aggressive IM treatment is likely associated with disease control and an overall favorable outcome.