Assays / Genetic Enzymes / Generalised Peroxisomal Disorders

The prototype of the generalised peroxisomal disorders is Zellweger syndrome. These patients have facial dysmorphia including high forehead, epicanthus and patent fontanelles. They are profoundly hypotonic and have severe psychomotor retardation, seizures and abnormal neuronal migration. There is fibrosis of the liver and cholestasis. Renal cysts are present and there is abnormal stippling in cartilage, usually confined to the patella and acetabulum. Patients rarely live for more than a few months but can survive to one year.

In patients with neonatal adrenoleucodystrophy there are similar features but they are somewhat milder. Adrenal atrophy and systemic lipid-laden macrophages are present but renal cysts and chondrodysplasia punctata are absent. Affected children can make some progress during their first year before regressing.

Children with infantile Refsum disease usually present at between 3 and 15 months of age with hepatodigestive symptoms. Pigmentary degeneration of the retina occurs and patients have sensorineural hearing loss and are severely retarded. Some slow progress may be made before regression occurs.

ENZYME TESTS: Dihydroxyacetone phosphate acyl transferase, fibroblast very long chain fatty acids, plasmalogen biosynthesis and catalase latency are assayed for the diagnosis of these disorders.

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