Abstract

2-hydroxyglutaric aciduria is a rare neurometabolic disorder characterized by the significantly elevated levels of hydroxyglutaric acid in ones urine. It is either autosomal recessive or autosomal dominant.

Presentation

The signs/symptoms of this condition are consistent with the following:

- Intellectual disability,

- Muscular hypotonia

- Encephalitis

- Seizures

- Aphasia

Diagnosis | Classification

2-hydroxyglutaric aciduria is an organic aciduria, and because of the stereoisomeric property of 2-hydroxyglutarate different variants of this disorder are distinguished:

Diagnosis | Classification | L-2-hydroxyglutaric aciduria

The L-2 form is more common, severe, and mainly affects the central nervous system. The basal ganglia are affected, and cystic cavitations in the white matter of the brain are common, beginning in infancy. This form is chronic, with early symptoms such as hypotonia, tremors, and epilepsy declining into spongiform leukoencephalopathy, muscular choreodystonia, mental retardation, and psychomotor regression.

It is associated with "L2HGDH," which encodes L-2-hydroxyglutarate dehydrogenase. L-2-hydroxyglutarate is produced by promiscuous action of malate dehydrogenase on 2-oxoglutarate, and L-2-hydroxyglutarate dehydrogenase is an example of a metabolite repair enzyme that oxidizes L-2-hydroxyglutarate back to 2-oxoglutarate.

Diagnosis | Classification | D-2-hydroxyglutaric aciduria

The D2 form is rare, with symptoms including macrocephaly, cardiomyopathy, mental retardation, hypotonia, and cortical blindness. It is caused by recessive mutations in "D2HGDH" (type I) or by dominant gain-of-function mutations in "IDH2" (type II).

Diagnosis | Classification | Combined D-2- and L-2-hydroxyglutaric aciduria

The combined form is characterized by severe early-onset epileptic encephalopathy and absence of developmental progress. It is caused by recessive mutations in "SLC25A1" encoding the mitochondrial citrate carrier.

Treatment

The treatment of 2-Hydroxyglutaric aciduria is based on seizure control, the prognosis depends on how severe the condition is.