Zellweger Baby Support Network

Have a question about Zellweger Syndrome or Peroxisomal disorders?  Find answers here:

What are peroxisomal disorders?

Peroxisomal disorders are a group of rare genetic disorders characterized by the absence of peroxisomes in the cells of the body.  There can also be a problem with the formation and/or function of the peroxisomes.

What are peroxisomes?

A peroxisome is one of four special compartments in the human cell. These individual compartments, known as organelles, are separated from the rest of the cell by a membrane (a "wall" made up of fats and proteins).  The peroxisome has two parts -- a peroxisome membrane and the peroxisome matrix.  The membrane actually surrounds the matrix.  Peroxisomes are a part of important cellular functions, such as beta-oxidation of very-long-chain fatty acids (VLCFA), production of plasmalogen, and synthesis of bile acid.

In order for the peroxisome to do its job properly it must be properly assembled.  Like anything else in the body, things can go wrong with the peroxisome, and this results in human disease. 

Different types of peroxisomal disorders:

Peroxisomal disorders can be classified into two (2) groups based on organelle structure and deficiencies. 

Group 1 includes peroxisomal biogenesis disorders (PBD) and result from a failure to form intact, normal peroxisomes, resulting in multiple metabolical abnormalities.  PBD's include the disorders of the Zellweger syndrome spectrum (ZSS).  There are three disorders considered to be part of the Zellweger spectrum: Zellweger Syndrome (ZS), Neonatal Adrenoluekodystrophy (NALD), and Infanile Refsum Disease (IRD).  Each of these three disorders have a similar cause and reflect varying degrees of severity, with ZS being the most severe and IRD the least severe.

Group 2 includes single enzyme deficiencies with intact peroxisomal structure.  There are at least 10 different disorders in which there is a deficiency of a single peroxisomal enzyme but the structure of the peroxisome is intact.  They fall under these catagories: peroxisomal beta-oxidation disorders, disorders of ether-phospholipid biosynthesis, and disorders of fatty-acid alpha-oxidation.

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Last updated: June 1, 2007