Inherited metabolic disorders
Glycogen storage disease
| Disorder | Deficient enzyme | Notes |
|---|---|---|
| Von Gierke's disease (type I) | Glucose-6-phosphatase | Hepatic glycogen accumulation. Key features include hypoglycaemia, lactic acidosis, hepatomegaly |
| Pompe's disease (type II) | Lysosomal alpha-1,4-glucosidase | Cardiac, hepatic and muscle glycogen accumulation. Key features include cardiomegaly |
| Cori disease (type III) | Alpha-1,6-glucosidase (debranching enzyme) | Hepatic, cardiac glycogen accumulation. Key features include muscle hypotonia |
| McArdle's disease (type V) | Glycogen phosphorylase | Skeletal muscle glycogen accumulation. Key features include myalgia, myoglobulinaemia with exercise |
Lysosomal storage disease
| Disorder | Defect | Notes |
|---|---|---|
| Gaucher's disease | Beta-glucocerebrosidase | Most common lipid storage disorder resulting in accumulation of glucocerebrosidase in the brain, liver and spleen. Key features include hepatosplenomegaly, aseptic necrosis of the femur |
| Tay-Sachs disease | Hexosaminidase A | Accumulation of GM2 ganglioside within lysosomes. Key features include developmental delay, cherry red spot on the macula, liver and spleen normal size (cf. Niemann-Pick) |
| Niemann-Pick disease | Sphingomyelinase | Key features include hepatosplenomegaly, cherry red spot on the macula |
| Fabry disease | Alpha-galactosidase-A | Accumulation of ceramide trihexoside. Key features include angiokeratomas, peripheral neuropathy of extemeties, renal failure |
| Krabbe's disease | Galactocerebrosidase | Key features include peripheral neuropathy, optic atrophy, globoid cells |
| Metachromatic leukodystrophy | Arylsulfatase A | Demyelination of the central and peripheral nervous system |
Mucopolysaccharidoses
| Disorder | Defect | Notes |
|---|---|---|
| Hurler syndrome (type I) | Alpha-1-iduronidase | Accumulation of glycosaminoglycans (heparan and dermatan sulfate). Key features include gargoylism, hepatosplenomegaly, corneal clouding |
| Hunter syndrome (type II) | Iduronate sulfatase | Accumulation of glycosaminoglycans (heparan and dermatan sulfate). Key features include coarse facial features, behavioural problems/learning difficulties short stature, no corneal clouding |