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Seven Patients With Transcobalamin Deficiency Diagnosed Between 2010 and 2014: A Single-Center Experience
Zuhal K Yildirim1, Ebba Nexo, Tony Rupar
1*Division of Pediatric Hematology/Oncology, Faculty of Medicine, Atatürk University, Erzurum §Division of Pediatric Hematology/Oncology, Faculty of Medicine, Sakarya University, Sakarya, Turkey †Department of Clinical Biochemistry, Aarhus University Hospital, Aarhus, Denmark ‡Departments of Biochemistry and Pediatrics, Children's Health Research Institute, University of Western Ontario, London, ON, Canada.
Insights
Transcobalamin deficiency, a rare genetic disorder, causes anemia and low platelets. Weekly cyanocobalamin (CN-Cbl) injections improve blood counts but do not prevent neurological delays.
Area of Science:
- Genetics
- Pediatrics
- Metabolic Disorders
Background:
- Transcobalamin deficiency is a rare autosomal recessive disorder.
- It presents with nonspecific clinical features in early infancy.
- Key early signs include anemia, thrombocytopenia, and hyperhomocysteinemia.
Purpose of the Study:
- To report the clinical and laboratory manifestations of seven children with transcobalamin deficiency.
- To evaluate the efficacy of cyanocobalamin (CN-Cbl) treatment on hematological and neurological outcomes.
Main Methods:
- Clinical and laboratory data from seven pediatric patients diagnosed with transcobalamin deficiency were reviewed.
- Genetic analysis identified a homozygous mutation in five patients.
- Treatment involved intramuscular cyanocobalamin (CN-Cbl) injections, initially daily, then weekly.
Main Results:
- All patients presented with anemia, thrombocytopenia, and hyperhomocysteinemia between 2-4 months of age.
- Genetic analysis revealed the same homozygous mutation in five patients.
- Weekly CN-Cbl injections improved hematological parameters but did not prevent speech and walking delays observed by 2-4 years of age.
Conclusions:
- Weekly intramuscular cyanocobalamin (CN-Cbl) is sufficient for hematological improvement in transcobalamin deficiency.
- However, this dosage is insufficient for normal neurological development.
- Treatment cessation or reduction led to relapse, highlighting the need for consistent therapy.
Abstract:
Transcobalamin deficiency (OMIM 275350) is a rare autosomal recessive disease presenting with nonspecific clinical features in early infancy. We report the clinical and laboratory manifestations of 7 children diagnosed with transcobalamin deficiency. All patients were admitted between 2 and 4 months of age with anemia, thrombocytopenia, and hyperhomocysteinemia. The most common complaints at admission were pallor, weakness, and poor feeding. Genetic analysis was performed in 5 patients and it revealed the same homozygous mutation. We initially treated all patients with intramuscular injections of a maximum of 1 mg cyanocobalamin (CN-Cbl) daily and with a final dose of 1 mg per week. Hemoglobin and platelet counts significantly decreased upon decrease or cessation of CN-Cbl therapy. The patients were reevaluated between 2 and 4 years of age and all had delay in speech and walking. In conclusion, 1 mg of intramuscular CN-Cbl every week suffices for hematological improvement but not for normal neurological development in patients who all had relapse due to decrease or cessation of treatment.
