In a storage disorder, a critical failure in a metabolic pathway prevents cellular breakdown and disposal of some large molecule.
In a metabolic or genetic pathway, enzymes catalyze a series of reactions.
Each enzyme is regulated or mediated by one gene through its RNA and protein products.
At each phase in the pathway, enzyme activity catalyzes a reaction in which a precursor molecule (the substrate) is transformed into its next intermediate state.
Failure of the metabolic pathway leads to accumulation of the substrate, with possible harmful effects.