====== Cobalamin C Disease ======
Methylmalonic acuduria with homocystinuria
====Main Features====
  * Most common inborn error of vitamin B12 metabolism
  * Early Onset (First year of life)
    * Neurologic & Cognitive Deterioration 
    * Pancytopenia
    * Megaloblastic anemia  
    * Progressive Retinopathy 
  * Later Childhood (>6 years) Onset
    * Gait abnormalities
    * Extrapyramidal symptoms
    * Psychiatric disturbances
    * Dementia
    * Cognitive Disability 
    * No retinopathy
====Eye Findings====
  * Retinopathy 
    * Spectrum from mild nerve fiber layer loss to advanced macular and optic nerve atrophy with "bone spicule" pigmentation 
    * Reduced ERG responses 
  * Nystagmus
====Other Findings====
  * Failure to thrive, poor feeding, vomiting
  * Microcephaly, brain malformations 
  * Hypotonia
  * Speech delay
  * Seizures
====Etiology====
  * Mutation in [[https://medlineplus.gov/genetics/gene/mmachc/|MMACHC gene]]
    * Gene product converts dietary [[https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/|vitamin B12]] to the metabolically active forms 
  * Treatment includes supplementation with: 
    * hydroxycobalamin
    * betaine
    * folinic acid 
====Reference====
  * {{ ::ocular_phenotype_in_patients_with_methylmalonic_aciduria_and_homocystinuria_cobalamin_c_type.pdf |Ocular Phenotype in Patients with methylmalonic aciduria and homocystinuria, cobalamin C type. J AAPOS 2008}}
  * {{ ::methylmalonic_aciduria_and_homocystinuria-associated_maculopathy.pdf |Methylmalonic aciduria and homocystinuria-associated maculopathy. Eye 2010}}
  * {{ ::the_adolescent_and_adult_form_of_cobalamin_c_disease-_clinical_and_molecular_spectrum.pdf |The Adolescent and adult form of cobalamin C disease: clinical and molecular spectrum. J Neurol Neurosurg Psychiatry 2008}}

{{tag>syndrome}}