Cobalamin C deficiency in an adolescent with altered mental status and anorexia

Maria H. Rahmandar*, Amanda Bawcom, Mary E. Romano, Rizwan Hamid

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Although cobalamin (cbl) C deficiency is the most common inherited disorder of vitamin B12 metabolism, the late-onset form of the disease can be difficult to recognize because it has a broad phenotypic spectrum. In this report, we describe an adolescent female exposed to unknown illicit substances and sexual abuse who presented with psychosis, anorexia, seizures, and ataxia. The patient 's diagnosis was delayed until a metabolic workup was initiated, revealing hyperhomocysteinemia, low normal plasma methionine, and methylmalonic aciduria. Ultimately, cblC deficiency was confirmed when molecular testing showed compound heterozygosity for mutations (c.271dupA and c.482G>A) in the MMACHC gene. This diagnosis led to appropriate treatment with hydroxocobalamin, betaine, and folate, which resulted in improvement of her clinical symptoms and laboratory values. This patient demonstrates a previously unrecognized presentation of late-onset cblC deficiency. Although neuropsychiatric symptoms are common in late-onset disease, seizures and cerebellar involvement are not. Furthermore, anorexia has not been previously described in these patients. This case emphasizes that inborn errors of metabolism should be part of the differential diagnosis for a teenager presenting with altered mental status, especially when the diagnosis is challenging or neurologic symptoms are unexplained. Correct diagnosis of this condition is important because treatment is available and can result in clinical improvement.

Original languageEnglish (US)
Pages (from-to)e1709-e1714
Issue number6
StatePublished - Dec 1 2014


  • Adolescent
  • Anorexia
  • Ataxia
  • Cobalamin C deficiency
  • Psychotic disorder

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health

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