Update on genetic and molecular investigations of diseases with general impairment of peroxisomal functions.

A group of genetically determined peroxisomal diseases is characterized by both multiple enzymatic deficiencies and abnormal structural features of the organelle. The primary cause of the phenotypes is likely to involve peroxisome assembly impairment. Complementation analyses performed on fibroblasts of patients revealed the existence of at least eight groups that do not reflect the clinical classifications. Recently, the use of experimental models led to the identification of a gene encoding for a peroxisomal membrane protein (PAF-1) in which a mutation was associated with the altered phenotype in a complementation group of the Zellweger syndrome (paradigm of these diseases). Also revealed in Zellweger probands are mutations of a gene encoding another peroxisomal protein (PMP70).