Methylmalonic Aciduria and Homocystinuria, cobalamin C (cblC) Type

Methylmalonic aciduria and homocystinuria, cblC type, is a defect in B12 metabolism. Patients may present with severe early onset disease that includes megaloblastic and macrocytic anemia and failure to thrive, microcephaly, lethargy and feeding difficulties. Neurologic symptoms may include hypotonia, seizures, developmental delay, ataxia and optic atrophy. Late onset cases may present with neurologic symptoms such as anorexia, irritability, fatigue, myelopathy or dementia. Other complications are mental retardation, microcephaly, retinal degeneration, pigmentary retinopathy, microangiopathy and skin lesions.

Tests Available

Forms and Documents

Test Details

  • Confirmation of a biochemical/clinical diagnosis
  • Carrier testing
  • Prenatal diagnosis in at risk pregnancies
  • Capillary Sequencing Reflex to Exon Array CGH


3-4 weeks
2-5 mL Blood - Lavender Top Tube
Oral Rinse (30-40 mL)|Buccal Swabs


  • 270.4 Disturbances of sulphur-bearing amino-acid metabolism, Cystathioninemia, Cystathioninuria, Disturbances of metabolism of methionine, homocystine, and cystathionine Homocystinuria, Hypermethioninemia, Methioninemia
  • 270.9 Unspecified disorder of amino-acid metabolism
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  1. Rosenblatt, DS and Fenton, WA (2001) Inherited disorders of folate and cobalamin transport and metabolism . In: C.R. Scriver, A.L. Beaudet, W.S. Sly and D. Valle (Eds)The Metabolic and Molecular Basis of Inherited Diseases, McGraw-Hill, NY
  2. Lerner-Ellis, JP et al., (2006) Nature Genet 38:93-100
  3. Rosenblatt, DS et al. (1985) Science 28:1319-1321
  4. Lerner-Ellis et al., (2009) Hum Mutat 30:1072-1081