Zellweger syndrome is a rare, inherited, fatal disorder that affects infants. The disorder is also known as generalized peroxisomal disorder, peroxisomal biogenesis disorder, Zellweger syndrome spectrum and ZSS.
Zellweger syndrome belongs to a group of diseases known as peroxisome biogenesis disorders (PBDs). These disorders are part of a larger group of diseases referred to as leukodystrophies, which are inherited conditions featured by progressive damage of the white matter of the brain.
Peroxisome biogenesis disorders include four diseases among which Zellweger syndrome is the most severe. Neonatal adrenoleukodystrophy and Rhizomelic chondrodysplasia have similar but less severe symptoms. The mildest of PBDs is infantile Refsum disease.
Causes of Zellweger Syndrome
PBDs are caused by genetic mutations that occur during brain development and formation of myelin, the white substance found in the cerebral cortex area. In Zellweger syndrome, genetic abnormalities lead to either reduction or lack of peroxisomes, cellular structures found in all body cells. Peroxisomes contain enzymes that play crucial role in variety of chemical reactions, such as cellular lipid metabolism and metabolic oxidation.
Since peroxisomes are abundantly found in the liver and kidney cells, their lack mainly affects those organs. In the absence of peroxisomes, toxins that enter the bloodstream do not get detoxified.
Symptoms of Zellweger Syndrome
Zellweger syndrome affects many major systems in the body. Individuals with the syndrome suffer from head and face abnormalities with signs such as enlarged head, high forehead, outer ear deformities, small chin, upslanting eyes and epicanthal folds. Eye abnormalities and vision problems like brushfield spots, abnormal retinal pigmentation, optic disk pallor, glaucoma and cataract occur as well.
Infants with Zellweger syndrome exhibit low muscle tone (hypotonia), severe weakness, slow reflexes and epileptic seizures. The symptoms in infants also include inability to move, poor sucking, difficulty swallowing and prenatal growth failure.
Zellweger syndrome is also characterized by elevated copper and iron in blood, enlarged liver (hepatomegaly), jaundice and gastrointestinal bleeding. Patients may have renal cysts and bone defects in the hands, legs and feet. Furthermore, Zellweger syndrome causes hearing impairment, profound mental retardation and developmental delay. Treatment for Zellweger Syndrome
The cure for Zellweger syndrome does not exist. Also, there is no standard course of treatment for the disease. Treatment for Zellweger syndrome is primarily supportive and symptomatic.
Infants born with Zellweger syndrome usually die within the first year of life. The death occurs most commonly due to gastrointestinal bleeding, respiratory distress or liver failure. Prevention of Zellweger Syndrome
Zellweger syndrome cannot be prevented. However, genetic counseling is recommended to individuals with family history of the disease. Couples who are carriers of the defective genes should be screened for the disorder before planning to have a child.