l-2-Hydroxyglutaric Aciduria

Inborn error of metabolism manifesting as progressive neurodegenerative disorder with psychomotor retardation.

The incidence is unknown, but approximately 20 cases have been reported. Transmission is autosomal recessive.

The enzymatic defect causing this progressive neurometabolic disorders is yet to be found. l-2-Hydroxyglutaric acid is a stereoisomer of d-2-hydroxyglutaric acid. Elevated levels of l-2-hydroxyglutaric acid are found in the urine, cerebrospinal fluid (CSF), and, to a lesser degree, in the serum. Plasma and CSF levels of lysine are elevated in some of these patients. In most patients, the initial symptoms are a delay of speech, unsupported walk and febrile seizures within the first 2 years of life. Over the following years, mental retardation associated to cerebellar ataxia with or without dystonia, pyramidal signs, and seizures develop. However, onset can be as early as neonatal age or as late as adolescent age. The oldest patient reported with this disorder was 57 years old. MRI scans reveal a consistent pattern with symmetrical subcortical leukoencephalopathy and cerebellar atrophy (vermis more than hemispheres). Furthermore, pathologic changes can—although inconsistently—be detected in the dentate nuclei, putamina, and globus pallidus.

Macrocephaly is a common feature, but no other facial anomalies have been reported, so airway management should not be affected. Keep in mind that these patients may be taking antiseizure medication, and potential interaction with other drugs and altered hepatic metabolism can occur.

Canavan Syndrome: Progressive leukodystrophy caused by spongy degeneration of the central nervous system. It is uniformly fatal.

d-2-Hydroxyglutaric Aciduria: Metabolic disease resulting in abnormal MRI findings and psychomotor retardation, hypotonia, and non neurologic signs.