[Combined methylmalonic aciduria and homocysteinemia with hydrocephalus as an early presentation: a case report].

A case of combined methylmalonic aciduria and homocysteinemia presenting with hydrocephalus as an early manifestation was reported for its rarity to see and to discuss the relationship between metabolic diseases and hydrocephalus by literature review. The case was an infant with seizures and hydrocephalus as an early manifestation of the disease, combined with macrocyticanemia, development retardation and visual hearing function lesions. The EEG showed hypsarrhythmia and the MRI showed hydrocephalus. Plasma homocysteinemia level increased (143.06 umol/L) and urine methylmalonic aciduria was 1483 times beyond normal. Based on gene analysis results and increased methylmalonic aciduria and homocysteinemia levels, combined methylmalonic aciduria and homocysteinemia was confirmed, presenting CblC defect (gene mutations homozygous for c.609G>A). After treatment by venous injection of vitamin B12, oral folic acid and betaine, seizures were controlled and development was progressive with ventricle retraction. It was concluded that hydrocephalus can be the early presentation in children with combined methylmalonic aciduria and homocysteinemia. Doctors should carry out metabolic disease screening for patients with hydrocephalus, especially when the cause of hydrocephalus is uncertain.