It is a group of four related diseases named as peroxisome biogenesis disorders (PBD). It is caused by the defects in the genes numbered 13, named as PEX genes, which are necessary for the normal functioning of the peroxisomes. Furthermore, the PBDs are subdivided into two main groups, Rhizomelic Chondrodysplasia Punctua spectrum and the Zellweger spectrum disorders.
Zellweger spectrum disorders
It is comprised of three disorders which are overlap with each other in terms of features. The three disorders are: neonatal adrenoleukodystrophy (NALD), Zellweger syndrome (ZS, the most severe form), and the Infantile Refsum disease (IRD, the tiniest unembellished form). As we known that the function of peroxisomes is to break down the toxic substances and in turn synthesize lipids, which are necessary for the proper functioning of the cell. Moreover, the peroxisomes are necessary for the proper functioning of the brain and its development, and forms myelin which is whitish substance covering the nerve fibers. Furthermore, they are also required for the proper functioning of liver, kidney, eye, and bone. The Zellweger spectrum disorder arises as result of the dysfunctional metabolism of lipid, which might be due to the over accumulation of long chain phytanic acids and fats, and in some cases due to the defects in the bile acids and lipids which are found in the cell membranes (plasmalogens–specialized lipids), and myelin sheath of nerve fibers.
Symptoms of Zellweger Syndrome
Common symptoms of Zellweger syndrome are:
- Enlarged Liver
- High forehead
- Wide set eyes
- Neurological abnormalities
- Underdeveloped eyebrow ridges
- Cognitive impairments
- Lack of muscle tone
- Movement problems
- Swallowing and sucking problem common in babies
- Few babies also born with glaucoma, impaired hearing, retinal degeneration, gastrointestinal bleeding and jaundice.
To the date no such treatment of Zellweger syndrome has been discovered, and there is no cure for it. As the most of the complications arises during fatal development, hence no such treatment is available to cure them after birth. However, most of the treatment practiced are only supportive and symptomatic.
It is a matter of fact that the prognosis for babies having Zellweger syndrome is very much deprived. Mostly, the babies don’t survive for more than 6 months, and are normally capitulate to the gastrointestinal bleeding, respiratory distress or liver failure.
The NINDs and some other institutes related to NIH are conducting research in which they are trying to explore the molecular and genetic based of the Zellweger syndrome and other related diseases. They also support the supplementary research via grants to major institutes.