mortality/aging
• if untreated, homozygotes die of fatal seizures at day P16-P22
• therapeutic intervention with anticonvulsants phenobarbital or phenytoin fails to ameliorate survival
• in contrast, intervention with vigabatrin or the GABAB receptor antagonist CGP 35348 prevents tonic-clonic convulsions and prolongs survival
• administration of taurine, which is derived from the metabolism of cysteine and is highly present in mother's milk, via drinking water (up to 5,000 mg/kg/d) provides rescue through the critical period
|
behavior/neurological
• at ~P15-P18, homozygotes display spasms and myoclonic seizures, leading to status epilepticus and death
|
• at about P15-P18, homozygotes display spasms and tonic seizures
|
• at P1-P16, unrestrained mutant neonates exhibit absence seizures identified by EEG analysis
|
growth/size/body
• homozygotes appear normal during the first days of life but display a 20-30% reduction in body weight relative to wild-type
|
homeostasis/metabolism
N |
• in mutant brain, the concentrations of glutamic acid and succinic acid are comparable to those of wild-type
(J:71949)
• homozygotes exhibit normal levels of Kreb's cycle intermediates in brain extracts, suggesting that global brain oxidative metabolism is unaffected
(J:75773)
|
• in brain extracts, P0-P18 homozygotes show high GABA/low glutamine both before and after the period of lethal tonic-clonic seizures
• brain homogenates show additional amino acid neurotransmitter abnormalities which may temporally correlate with the onset of lethal convulsions
|
• homozygotes exhibit normal levels of total beta-alanine in urine and total homogenates of mutant brain, heart and pancreas, but elevated concentrations in kidney and liver homogenates
|
• in mutant liver and brain homogenates, the amounts of GHB and total GABA are increased 30-45 and 2.5-3 fold, respectively, relative to wild-type
(J:71949)
• homozygotes show elevated amounts of GHB and total GABA in homogenates of mutant kidney, pancreas and heart
(J:75773)
• in brain extracts, P0-P18 homozygotes show high GABA/low glutamine both before and after the period of lethal tonic-clonic seizures
(J:91856)
|
• homozygotes contain elevated amounts of gamma-hydroxybutyric (GHB) and total 4-aminobutyric acid (GABA) in urine
|
• homozygotes show a significant reduction of glutamine in mutant brain homogenates, despite normal glutamine synthetase protein and mRNA levels
(J:75773)
• in brain, glutamine depletion is detected in the frontal cortex, parietal cortex, hippocampus and cerebellum
(J:75773)
• however, glutamine levels are normal in mutant liver and kidney extracts
(J:75773)
• in brain extracts, P0-P18 homozygotes show low glutamine both before and after the period of lethal tonic-clonic seizures
(J:91856)
|
muscle
• at ~P15-P18, homozygotes display spasms and myoclonic seizures, leading to status epilepticus and death
|
renal/urinary system
• homozygotes contain elevated amounts of gamma-hydroxybutyric (GHB) and total 4-aminobutyric acid (GABA) in urine
|
nervous system
• at ~P15-P18, homozygotes display spasms and myoclonic seizures, leading to status epilepticus and death
|
• at about P15-P18, homozygotes display spasms and tonic seizures
|
• at P1-P16, unrestrained mutant neonates exhibit absence seizures identified by EEG analysis
|
• at P1-P16, unrestrained mutant neonates exhibit absence seizures identified by EEG analysis
|