Degenerative developmental diseases

• Usually caused by inborn errors of metabolism
• development may proceed normally, then arrests and regresses (different from a malformation)
• defects may be in lysosomal enzymes, cofactors or membrane receptors
• one or more enzyme/facotr may be defective or missing
• defects may result in accumulation of abnormal metabolites (storage diseases) in neurons, glia, macrophages, and in some diseases in other tissues in the body.
  • These may be seen histologically, histochemically and ultrastructurally on biopsy and autopsy material.
  • If white matter is involved, hypo/dysmyelination is present (leukodystrophy)
• defective enzyme or its accumulated metabolite may be measured chemically for diagnosis
  • the gene responsible may be diagnosable
• the defective enzymes are lysosomal or peroxisomal
• the diseases may predominantly affect the grey or white matter, or both
• diseases may be classified by the type of substance accumulated, eg. gangliosidosis
• all may have variety of clinical forms with different rates of expression

Grey Matter Diseases

White Matter Diseases