Saccharopinuria

Saccharopinuria is a disorder of lysine metabolism associated with hyperlysinaemia and lysinuria.

Epidemiology

The prevalence is unknown.

Clinical description

The few patients with saccharopinuria have been investigated largely because of neurological problems including spastic diplegia but the relationship between the saccharopinuria and these is unclear.

Etiology

It is caused by a deficiency in the bifunctional enzyme alpha-aminoadipate semialdehyde synthase, encoded by the AASS gene (located at 7q31.3). This enzyme has both lysine-ketoglutarate reductase (LKR) and saccharopine dehydrogenase (SDH) activity, and catalyses the first two steps of lysine degradation. In saccharopinuria, deficiency of the LKR activity is only partial.

Genetic counseling

Saccharopinuria is an autosomal recessive disorder.

Management and treatment

There is no specific treatment for the disease but a low lysine diet may be beneficial in some cases.