Arakawa's syndrome II is an inborn error of metabolism, a genetic 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. 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. Inheritance is autosomal dominant. The following codes are used with International Statistical Classification of Diseases and Related Health Problems. ... The following is a list of codes for International Statistical Classification of Diseases and Related Health Problems. ... The International Classification of Diseases for Oncology (ICD-O) is a domain specific extension of the International Statistical Classification of Diseases and Related Health Problems for tumor diseases. ... The Mendelian Inheritance in Man project is a database that catalogues all the known diseases with a genetic component, and - when possible - links them to the relevant genes in the human genome. ... The Diseases Database is a free website that provides information about the relationships between medical conditions, symptoms, and medications. ... MedlinePlus (medlineplus. ... eMedicine is an online clinical medical knowledge base that was founded in 1996. ... Inborn errors of metabolism comprise a large class of genetic diseases involving disorders of metabolism. ... A genetic disorder, or genetic disease is a disease caused by abnormal expression of one or more genes in a person causing a clinical phenotype. ... Chemical structure of Vitamin B12 The name vitamin B12 (or B12 for short) is used in two different ways. ... Neurology is a branch of medicine dealing with the nervous system and its disorders. ... Mental retardation (also called mental handicap and, as defined by the UK Mental Health Act 1983, mental impairment and severe mental impairment) is a term for a pattern of persistently slow learning of basic motor and language skills (milestones) during childhood, and a significantly below-normal global intellectual capacity as... Atrophy is the partial or complete wasting away of a part of the body. ... The ventricular system is a set of structures in the brain continuous with the central canal of the spinal cord. ... Myoclonus is brief, involuntary twitching of a muscle or a group of muscles. ... Hypotonia is a condition of abnormally low muscle tone (the amount of tension or resistance to movement in a muscle), often involving reduced muscle strength. ... Megaloblastic anemia is anemia resulting from a deficiency of vitamin B12 and folic acid. ... A teenager with pectus excavatum Pectus Excavatum is a congenital deformity that causes the sternum to be depressed into the chest causing a caved-in look. ... Vomiting (or emesis) is the forceful expulsion of the contents of ones stomach through the mouth. ... Diarrhea (American English) or diarrhoea (Commonwealth English) is a condition in which the sufferer has frequent and watery, chunky, or loose bowel movements (from the ancient Greek word διαρροή = leakage; lit. ... Hepatosplenomegaly is the simultaneous enlargement of both the liver (hepatomegaly) and the spleen (splenomegaly). ... An autosomal dominant gene is an abnormal gene on one of the autosomal (non-sex determining) chromosomes. ...

Reference

T. Arakawa, et al: Megaloblastic anaemia and mental retardation associated with hyperfolicacidaemia. Probably due to N-5 methyltetrahydrofolate transferase deficiency. Tohoku Journal of Experimental Medicine, Sendai, 1967, 93: 1-22.