title: Arakawa's syndrome II
text: # Arakawa's syndrome II
  
  Arakawa's syndrome II is an autosomal dominant metabolic disorder that causes a deficiency of the enzyme tetrahydrofolate-methyltransferase; affected individuals cannot properly metabolize methylcobalamin, a type of Vitamin $B_{12}.$
  
  ## Presentation
  
  This disorder causes neurological problems, including intellectual disability, brain atrophy and ventricular dilation, myoclonus, hypotonia, and epilepsy.
  
  It is also associated with growth retardation, megaloblastic anemia, pectus excavatum, scoliosis, vomiting, diarrhea, and hepatosplenomegaly.
  
  ## Genetics
  
  Arakawa's syndrome II is inherited in an autosomal dominant manner. This means the defective gene responsible for disorder is located on an autosome, and one copy of the defective gene is sufficient to cause the disorder when inherited from a parent who has the disorder.
  
  ## Eponym
  
  It is called "Arakawa syndrome 2" after Tsuneo Arakawa (1949–2003), a Japanese Physician.; in this context, "Arakawa syndrome 1" refers to Glutamate formiminotransferase deficiency.
  
  