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Update on transcobalamin deficiency: clinical presentation, treatment and outcome
Y J Trakadis1, A Alfares, O A Bodamer
1Department of Medical Genetics, McGill University Health Centre, Montreal, QC, Canada, john.trakadis@mail.mcgill.ca.
Insights
Transcobalamin (TC) deficiency, a rare genetic disorder, requires regular cobalamin injections for treatment. This study evaluates treatment strategies and long-term outcomes in 30 patients, finding weekly intramuscular injections beneficial.
Area of Science:
- Genetics and Molecular Biology
- Hematology
- Pediatric Endocrinology
Background:
- Transcobalamin (TC) deficiency is a rare autosomal recessive disorder affecting cobalamin transport into cells.
- Clinical presentation includes failure to thrive, anemia, pancytopenia, and immunodeficiency, mimicking other severe infant conditions.
- Diagnostic indicators include megaloblastic anemia, elevated homocysteine, and methylmalonic acid levels.
Purpose of the Study:
- To evaluate treatment strategies and long-term patient outcomes for Transcobalamin (TC) deficiency.
- To provide evidence-based recommendations for cobalamin administration in TC deficiency.
- To analyze data from a cohort of 30 TC deficiency patients.
Main Methods:
- Retrospective analysis of 30 patients with Transcobalamin (TC) deficiency.
- Review of treatment regimens, including cobalamin type, route, and frequency.
- Monitoring of clinical status, complete blood count (CBC), plasma homocysteine, and methylmalonic acid levels.
Main Results:
- Intramuscular injections of hydroxy- or cyanocobalamin are the preferred treatment method.
- Weekly 1 mg intramuscular injections were often necessary for optimal treatment.
- Treatment regimens were individualized based on regular monitoring of key biomarkers and clinical status.
- Continuous intramuscular treatment into adulthood demonstrated long-term benefits.
Conclusions:
- Regular intramuscular cobalamin administration is effective for managing Transcobalamin (TC) deficiency.
- Individualized treatment adjustments based on monitoring are crucial for optimal outcomes.
- Long-term intramuscular treatment is beneficial for patients with TC deficiency throughout their lives.
Abstract:
Transcobalamin (TC) transports cobalamin from blood into cells. TC deficiency is a rare autosomal recessive disorder usually presenting in early infancy with failure to thrive, weakness, diarrhoea, pallor, anemia, and pancytopenia or agammaglobulinemia. It can sometimes resemble neonatal leukemia or severe combined immunodeficiency disease. Diagnosis of TC deficiency is suspected based on megaloblastic anemia, elevation of total plasma homocysteine, and blood or urine methylmalonic acid. It is confirmed by studying the synthesis of TC in cultured fibroblasts, or by molecular analysis of the TCN2 gene. TC deficiency is treatable with supplemental cobalamin, but the optimal type, route and frequency of cobalamin administration and long term patient outcomes are unknown. Here we present a series of 30 patients with TC deficiency, including an update on multiple previously published patients, in order to evaluate the different treatment strategies and provide information about long term outcome. Based on the data presented, current practice appears to favour treatment of individuals with TC deficiency by intramuscular injections of hydroxy- or cyanocobalamin. In most cases presented, at least weekly injections (1 mg IM) were necessary to ensure optimal treatment. Most centres adjusted the treatment regimen based on monitoring CBC, total plasma homocysteine, plasma and urine methylmalonic acid, as well as, clinical status. Finally, continuing IM treatment into adulthood appears to be beneficial.
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