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Late-onset cobalamin C disease: rare but treatable
  1. Aminu Aliyar1,
  2. Mounika Endrakanti2,
  3. Rajesh K Singh1,
  4. Arunmozhimaran Elavarasi1,
  5. Neerja Gupta2,
  6. Deepti Vibha1,
  7. Manjari Tripathi1
  1. 1Neurology, All India Institute of Medical Sciences, New Delhi, India
  2. 2Division of Genetics, Department of Paediatrics, All India Institute of Medical Sciences, New Delhi, India
  1. Correspondence to Dr Rajesh K Singh, Neurology, AIIMS, New Delhi 110029, India; drrajeshrims679{at}


Cobalamin C disease is the most common inborn error of cobalamin metabolism, resulting from mutations in methylmalonic aciduria and homocystinuria type C protein (MMACHC) gene. There is associated elevation of homocysteine and methylmalonic acid and decreased synthesis of methionine. It is a multisystem disorder characterised by cognitive impairment, psychiatric manifestations, haematological manifestations and thromboembolic phenomena. Its variable clinical presentation and wide age distribution at presentation necessitates a high index of diagnostic suspicion. The diagnosis is suggested by amino acid chromatography and confirmed by sequencing analysis of the MMACHC gene. Parenteral hydroxycobalamin and betaine can bring significant clinical and biochemical improvement and is the recommended long-term therapy.


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  • Contributors All authors contributed in the diagnosis and management of the patient and in writing the manuscript.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed by Robin Lachmann, London, UK.

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