Non-ketotic hyperglycinemia (NKH). Juvenile or late onset form.
Incidence
Very rare.
Clinical Characteristics
In this form there is mild mental retardation, hyperactivity and language deficits. Present as a spinal cerebellar degeneration. Valproate therapy may lead to elevation of CSF and/or plasma glycine levels by inhibition of the glycine cleavage system and would therefore best be avoided in NKH, whether of neonatal or
later onset.
Precipitants
No. However Valproate therapy may lead to elevation of CSF and/or plasma glycine levels by inhibition of the glycine cleavage system and would therefore best be avoided in NKH, whether of neonatal or later onset.
Provocation Tests
no
Diagnostic Procedures
CSF glycine and CSF/plasma ratio elevated. The ratio of CSF glycine to plasma glycine is much higher than in patients with organic acidurias (0.1-0.3; normal 0.01-0,03)