- Comprise a big class of genetic diseases dealing with congenital disorders of metabolism. A huge part of the diseases are due to single gene defects that code for enzymes that help conversion of various substances (substrates) into others (products).
- In most of the disorders, problems appear because of substance build-up which are toxic or interfere with normal function, or to the effects of decreased ability to synthesize essential compounds.
- Other names: congenital metabolic diseases, inherited metabolic diseases.