Peroxisomal disorders: An updating

Genetic diseases in man in which peroxisomal functions are impaired may be divided into three categories. A. Diseases in which morphologically distinguishable peroxisomes (defined as catalase-positive particles) are deficient and most peroxisomal functions are impaired. This category comprises the Zellweger syndrome, Infantile Refsum disease and Neonatal Adrenoleukodystrophy. B. Diseases in which catalase-positive particles are present but in which some peroxisomal functions are impaired. The Rhizomelic form of Chondrodysplasia Punctata and the Zellweger-like syndrome belong to this category. C. Diseases in which a single peroxisomal enzyme is deficient. This category includes diseases characterized by a deficiency of one of the following enzymes: peroxisomal very-long-chain acyl-CoA synthetase (X-linked Adrenoleukodystrophy); acyl-CoA oxidase (pseudo-Neonatal Adrenoleukodystrophy); bifunctional protein; peroxisomal 3-oxoacyl-CoA thiolase (Pseudo-Zellweger syndrome); alanine: glyoxylate aminotransferase (Hyperoxaluria type 1); and catalase (Acatalasaemia). It is at present not clear whether adult Refsum disease (deficiency of phytanic acid α-hydroxylase) should be classified as a peroxisomal disorder or not.