Metabolic Pathways includes descriptions and detailed diagrams of numerous metabolic pathways, such as those involved in the metabolism of carbohydrates, energy, lipids, nucleoides, amino acids, macromolecules, and others.

http://www.genome.ad.jp/dbget-bin/get_htext?/Metabolism

A number of human disorders arise from genetic defects in metabolic pathways. Galactosemia is one such disease that leads to cirrhosis in infants and can be devastating. Another inherited metabolic pathway disorder is Maple Syrup Urine Disease (MSUD) that is rare but affects the body's processing of certain amino acids.

http://www.gastro.com/liverpg/galactos.htm

http://www.msud-support.org/descrip.htm