A new autosomal recessive syndrome with Zellweger-like manifestations

Zellweger syndrome and secondary mitochondrial myopathy

Defects in peroxisomes such as those associated with Zellweger syndrome (ZS) can influence diverse intracellular metabolic pathways, including mitochondrial functioning. We report on an 8-month-old female infant and a 6-month-old female infant with typical clinical, radiological and laboratory features of Zellweger syndrome; light microscopic and ultrastructural evidence of mitochondrial pathology in their muscle biopsies; and homozygous pathogenic mutations of the PEX16 gene (c.460 + 5G > A) and the PEX 12 gene (c.888_889 del p.Leu297Thrfs*12), respectively. Additionally, mitochondrial respiratory chain enzymology analysis in the first girl showed a mildly low activity in complexes II-III and IV. We also review five children previously reported in the literature with a presumptive diagnosis of ZS and additional mitochondrial findings in their muscle biopsies. In conclusion, this is the first study of patients with a molecularly confirmed peroxisomal disorder with features of a concomitant mitochondrial myopathy and underscores the role of secondary mitochondrial dysfunction in Zellweger syndrome, potentially contributing to the clinical phenotype.

Recognition of Zellweger syndrome in infancy

At least 29 proteins are required for assembly of the peroxisome, a single-membrane organelle responsible for many metabolic processes. A defect in any of these proteins affects the numerous biochemical functions of the cell. Many genetic disorders are associated with peroxisome defects. Zellweger syndrome, a rare autosomal recessive disorder, is one of the disorders that result from a deficiency in the assembly of the peroxisome. Impaired metabolism results in the accumulation of toxic metabolites and damages developing neural cells. This article provides an overview of peroxisome function and its effect on central nervous system development. It highlights the presentation, clinical features, and nursing care of infants with Zellweger syndrome. A meticulous systematic physical assessment enhances early recognition of the physical features of this disorder. Although magnetic resonance imaging detects polymicrogyria, a manifestation of abnormal neuronal migration that is often associated with Zellweger syndrome, the diagnosis is confirmed biochemically. An emphasis on family support through genetic counseling and the integration of palliative resources to enhance quality of life for infants and families with this lethal condition is provided.