Zellweger spectrum disorders

Zellweger Spectrum Disorders (ZSDs) are a group of rare, genetic, metabolic disorders characterized by the reduction or absence of peroxisome functions in the cells. These disorders represent a spectrum of diseases that were previously classified as separate entities, including Zellweger syndrome, neonatal adrenoleukodystrophy, and Infantile Refsum disease. ZSDs are part of a larger group of diseases known as peroxisomal biogenesis disorders (PBDs), which are caused by mutations in any one of the PEX genes responsible for the normal assembly and functioning of peroxisomes.

Symptoms and Diagnosis

The symptoms of ZSDs can vary widely among affected individuals, even within the same family. They can range from mild to severe and may include hypotonia (low muscle tone), seizures, hearing and vision impairments, liver dysfunction, developmental delays, and distinctive facial features. The most severe form, Zellweger syndrome, presents life-threatening symptoms in the newborn period.

Diagnosis of ZSDs involves a combination of clinical evaluation and laboratory testing. This may include blood tests to measure very long-chain fatty acids (VLCFAs), which are typically elevated in ZSDs, as well as genetic testing to identify mutations in the PEX genes.

Treatment and Management

There is currently no cure for ZSDs, and treatment is primarily supportive and symptomatic. Management strategies may include physical therapy, hearing aids, glasses, nutritional support, and medications to manage seizures and other symptoms. Liver transplantation has been performed in some cases of severe liver dysfunction.

Genetics

ZSDs are inherited in an autosomal recessive manner, meaning that an individual must inherit two mutated copies of the relevant PEX gene, one from each parent, to be affected. Parents of an affected child are typically carriers of one mutated gene. Genetic counseling is recommended for families with a history of ZSDs.

Research

Research into ZSDs is focused on understanding the complex biology of peroxisomes and developing treatments that can target the underlying genetic defects. Gene therapy and cell therapy are areas of active investigation.

NIH genetic and rare disease info

• NIH info on Zellweger spectrum disorders

Zellweger spectrum disorders is a rare disease.