What are Peroxisomal Disorders?
Peroxisomal Disorders are the name given to a group of congenital disorders which develop due to abnormal or complete absence of peroxisomes within the body cells. Anatomically, peroxisomes are organelles which produce enzymes required for major chemical process within the cells. Within a cell, there may be several hundred of peroxisomes which are normally round or oval shaped and contain proteins used for various metabolic activities in the body.
Peroxisomal disorders are divided into two main categories. The first category known as peroxisome biogenesis disorders there is failure of formation of an intact peroxisome which ultimately leads to variety of metabolic disorders. In the second category, the structure of the peroxisome is normal nut there is deficiency of protein present in the organelle which again causes variety of metabolic abnormalities.
Studies state that in every peroxisome about 50 chemical reactions take place of which some are known as anabolic and some are catabolic reactions. Anabolic reactions are also known as constructive reactions and involve chemical processes which combine various compounds like the bile and cholesterol.
The catabolic reactions are destructive reactions and are responsible for breaking down very long chain fatty acids to smaller forms so that they can be used by the body for various processes or be eliminated from the body.
If the peroxisomes are not able to break down these very long chain fatty acids there is accumulation of these compounds which affect the entire structure and functionality of the cells especially those of the central nervous system. It ultimately results in genetic conditions medically referred to as leukodystrophy. Some of the examples of peroxisomal diseases are:
X-linked Adrenoleukodystrophy which is a gender related disease which have primary presenting features of muscle weakness, speech problems, and behavioral abnormalities that progress as the individual ages.
Zellweger Syndrome. This is one of the most serious peroxisomal disorder to which the child usually succumbs to within the first year of life.
Infantile Refsum Disease. this disease may not be fatal but leaves a child with severe motor, cognitive, and speech difficulties although the child may regain some of it back with aggressive therapies.
What Is The Cause Of Peroxisomal Disorders?
The reason as to why there are abnormalities in the shape and functionality of the peroxisomes are not clearly understood. In some diseases that come under peroxisomal disorders there is complete absence or nonfunctioning organelle like the Zellweger Syndrome where the chances of the child surviving are minimal. There are also certain disorders like the Infantile Refsum Disease in which some part of the peroxisome still functions and the disease is not that deadly.
In some cases, the structure of the peroxisome is intact but just the proteins that the organelle has is missing interfering with the metabolic process. Diseases caused due to this malfunction may equally be deadly but that is not always the case.
What Are The Symptoms Of Peroxisomal Disorders?
Generally speaking, the primary presenting features of peroxisomal Disorders include delays in overall development of the baby. The child also suffers from mental retardation. Additionally, hearing, speech, and vision disturbances are common occurrences in children with peroxisomal disorders.
Children who tend to survive the complications of this disorder tend to have autism later on in life. Hypotonia is also quite common in children with Peroxisomal Disorders which is normally generalized but in extreme cases is severe at the trunk and neck.
Children with peroxisomal disorders also have delay in reaching their developmental milestones with delay in sitting and ambulation. Some of the other symptoms of Peroxisomal Disorders are:
- Failure to thrive
- Liver function abnormalities
- High frontal forehead
- Frontal bossing
- Abnormally small face
- Low set ears
How are Peroxisomal Disorders Diagnosed?
The diagnosis of Peroxisomal Disorders cannot be made by just the symptoms that the patient experiences as some of the symptoms like learning and speech difficulties are common to many other conditions as well. However, symptoms like failure to thrive, prominent facial features, and liver dysfunction definitely points towards this diagnosis.
If Peroxisomal Disorders is suspected in a child then further investigations with blood plasma assay for accumulation of long chain fatty acids can also be done to confirm the diagnosis.
If a female carries a risk of Peroxisomal Disorders then the diagnosis can also made before birth of the child. Conditions like X linked adrenoleukodystrophy can be diagnosed by analyzing the amniotic fluid. It can diagnose approximately 90% of cases of Peroxisomal Disorders in utero in the first trimester of pregnancy.
How are Peroxisomal Disorders Treated?
Unfortunately, there is no cure for Peroxisomal Disorders or a standardized mode of treatment. Treatment is mainly aimed at preventing complications and easing the symptoms with supportive measures. For cases of X linked adrenoleukodystrophy a bone marrow transplant has shown some efficacy if done very early in the child’s life normally before the child is two years of age.
Physical therapy is a must for all diseases that come under Peroxisomal Disorders along with psychological support to cope with the illness. There are also certain alternative forms of treatment like a mixture of rapeseed and olive oil that has shown some efficacy in especially treating X-linked adrenoleukodystrophy along with other disease conditions that come under Peroxisomal Disorders.
Proper nutrition is also quite important in children with Peroxisomal Disorders. Diet is important to correct the cellular abnormalities seen with Peroxisomal Disorders. Children with this disorder should absolutely avoid any intake of fatty food and stick to foods rich in antioxidants and vitamins.
Giving pure form of DHA very early in the child’s life is being studied for its effect in preventing complications like vision disturbance and cognitive impairment along with damage to the structures of the brain.
What are the Prognosis of Peroxisomal Disorders?
Peroxisomal Disorders do not have a cure. While some diseases which come under these disorders are life threatening there are some diseases which may not be life threatening but can definitely make the child permanently disabled.