Arakawa's syndrome II

Arakawa's syndrome II
Classification and external resources
methylcobalamin
OMIM	156570
DiseasesDB	32787

Arakawa's syndrome II^[1] 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 B₁₂.

It is also called Methionine synthase deficiency, Tetrahydrofolate-methyltransferase deficiency syndrome, and N5-methylhomocysteine transferase deficiency.^[2]

Characteristics

This disorder causes neurological problems, including mental retardation, 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 has an autosomal dominant pattern of inheritance.

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;^[1][3] in this context, "Arakawa syndrome 1" refers to Glutamate formiminotransferase deficiency.

References

1. ^ ^{a b} synd/235 at Who Named It?
2. ^ Online 'Mendelian Inheritance in Man' (OMIM) 156570
3. ^ Arakawa T, et al. (1967). "Megaloblastic anemia and mental retardation associated with hyperfolic-acidemia: probably due to N5 methyltetrahydrofolate transferase deficiency". Tohoku J. Exp. Med. 93 (1): 1–22. doi:10.1620/tjem.93.1. PMID 5300832. 

External links

• Arakawa's syndrome 2 at NIH's Office of Rare Diseases