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Glycogen debranching enzyme defect in muscle & liver
Hepatomegaly, hypoglycemia, growth retardation, progressive skeletal myopathy, cardiomyopathy.
glycogen debranching enzyme defect in liver.
Defect in branching enzymes leads to long unbranched insoluble glycogen that precipitates in liver.
Hepatomegaly and liver cirrhosis -> death at age 5.
Defect in muscle phosphorylase.
- Exercise intolerance & muscle cramps
- no CORI-cycle
- rhabdomyolysis -> renal failure
TX: Glucose before exercise
Defect in liver phosphorylase
- Mild to moderate hypoglycemia
- mild ketosis
- growth retardation
- prominent hepatomegaly
defect in muscle phosphofructokinase
- Exercise intolerance w/ cramps
- rhabdomyolysis & myoglobinuria
- Gout as Fru-6 -> hexose monophosphate pathway
Defect hepatic phosphorylase kinase (x-linked)
- growth retardation
- elevated liver enzymes
- fasting hyperketosis
- Dec Glucose uptake/release by liver
- dec glucose sensing in pancreas
- dec reuptake in renal tubules
- growth failure
- moon-shaped face
- fats deposits on shoulder & abd
- Glucose, aa, phosphate, pro and uric acid in urine
- metabolic acidosis
TX: antiketogenic diet, water, electrolyte, and vitamin D supplementation
Lysosomal sotrage diseases
- Accumulation of substrate in lysosome & ECM
- prevents autophagosome-lysosome fusion
- inflammation via Toll-receptors
- apoptosis via growth factors
- cholesterol metabolism & insulin signaling affected
- lysosphingolipids interfere with cell signal & cytokines -> apoptosis; giant multinuclear cells
- Ca2+ release after inc Glucose -> exitotoxicity. Low Ca2+ -> apoptosis
Lysosomal storage disease tx
Enzyme with Man-6-P binds to cellular receptor -> endocytosis -> transport to lysosome
Muscles and nervous system most affected.
3 enzymes that could be affected
- lactic & pyruvic acidemia
- poor feeding
- developmental delay
Pyruvate DH E1
inactivated by phosphorylation by PDH-kinase.
-> lactic acidosis in children
Mutation in OxPhos or PDH
Early onset progressive neurodegeneration with focal, bilateral lesions in CNS: demyelination, gliosis, necrosis, spongiosis, or capillary proliferation.
lactic acidosis, tachypnea, truncal hyptonia, growth retardation, cardiomyopathy, encephalopathy, myoclonic epilepsy
Inheritance mitochondrial or AR
LEBER hereditary optic neuropathy
Acute or subacute central vision loss leading to central
- scotoma (blind-spot) or blindness in mid-age
- neurologic manifestations in some cases
- susceptibility for tobacco-alcohol amblyopia
- various mutations in mtDNA for complex I, III, and IV
RAGGED RED FIBERS
Lumps of aggregated mitochondria in muscle biopses, staining red with GOMORI's trichome