Pyruvate dehydrogenase (PDH) deficiency. E1 subunit deficiency (Neonatal form). Also called Pyruvate decarboxylase deficiency (PDC defic)
Incidence
Very rare. Never seen in Saudi Arabia. Most patients male (gene located in chromosome X). It may occur in mild degree in heterozygous females.
Clinical Characteristics
The most common cause of neonatal primary lactic acidosis. This neonatal form shows severe intrauterine growth retardation. They have lethargy, tachypnea, respiratory distress, vomiting and coma neonatally. Extreme hypotonia. Seizures in 1/3 of patients. Dysmorphic features and congenital anomalies have been reported in 1/4 of cases, such as a narrow head, frontal bossing, hydrocephalus, broad nasal bridge, upturned nose, micrognathia, low set ears, simiam creases, short arms and fingers, hypospadia and anteriorly placed anus. Most pts. usually die in the first few months of life.
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-F, EB-muscle, EB-liver, EB-brain, EB-kidney, OB-F, DB-F (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.