Pyruvate dehydrogenase (PDH) deficiency. E1 subunit deficiency (lnfantile form). Also called pyruvate decarboxylase deficiency (PDC defic)
Incidence
Very rare. 3 times more common than the neonatal form and less severe. 3 cases in Saudi Arabia.
Clinical Characteristics
It is the classic Leigh disease. Death occurs between 10-36 mo. Intrauterine growth retardation invariable will be noted by 6 months of pregnancy. Born with severe SGA. They have very abnormal breathing pattern, apneas followed by sighing. They may present with uncharacteristic psychomotor retardation, seizures, pyramidal signs, deceleration of head growth and mild dysmorphic features. Lactic acid can be elevated or normal in blood but always elevated in CSF.
Precipitants
None
Provocation Tests
Glucose loading (1 g/kg IV) or L-Alanine loading (110 to 200 mg/kg IV) leads to sustained hyperlactic acidemia.
Diagnostic Procedures
EB-muscle, EB-liver, EB-brain, EB-kidney. (DNA studies). L/P ratio < 25. Some times lactic acid is normal in blood but abnormal in CSF, so an LP should be done to check for lactic acid in CSF.