Allogeneic Hematopoietic Stem Cell Transplantation for PEX1-Related Zellweger Spectrum Disorder: A Case Report and Literature Review

Zellweger spectrum disorder presenting with opsoclonus-myoclonus-ataxia syndrome: a case report on immunotherapy

INTRODUCTION

Zellweger spectrum disorder (ZSD) refers to a group of autosomal recessive genetic disorders that affect multiple organ systems and are predominantly caused by pathogenic variants in PEX genes. ZSD present a wide clinical spectrum, ranging from the most severe form, Zellweger syndrome, to the mildest form, Heimler syndrome.

CASE REPORT

A 14-month-old male patient was brought to our clinic with recent-onset ocular tremors and unsteady gait. Based on the preliminary suspicion of an infection-related autoimmune disease, the patient received intravenous immunoglobulin (IVIG) and pulse steroid therapy. Although initial clinical improvement was observed in opsoclonus and ataxia, ocular symptoms later recurred. Peroxisomal profile revealed elevated plasma levels of phytanic acid, pristanic acid, and very long-chain fatty acids (C26), raising suspicion for ZSD. Consequently, dietary restrictions for very long-chain fatty acids, phytanic acid, and pristanic acid, along with vitamin supplementation (A, D, E, and K), were initiated. Molecular genetic testing identified a homozygous c.2528G > A, p.(Gly843Asp) pathogenic variant in the PEX1 gene, confirming the diagnosis.

CONCLUSION

Zellweger spectrum disorder presents with a wide range of clinical manifestations. While no effective treatment currently exists, a diet restricted in very long-chain and branched-chain fatty acids, supplementation with vitamins A, D, E, and K, and bile acid therapy are commonly used. In our patient, IVIG and pulse steroid therapy were administered due to a preliminary suspicion of an autoimmune process, resulting in a short-term partial clinical response. To our knowledge, the use of immunotherapy in ZSD has not been previously reported in the literature.

Peroxisome deficiency underlies failures in hepatic immune cell development and antigen presentation in a severe Zellweger disease model

Peroxisome biogenesis disorders (PBDs) represent a group of metabolic conditions that cause severe developmental defects. Peroxisomes are essential metabolic organelles, present in virtually every eukaryotic cell and mediating key processes in immunometabolism. To date, the full spectrum of PBDs remains to be identified, and the impact PBDs have on immune function is unexplored. This study presents a characterization of the hepatic immune compartment of a neonatal PBD mouse model at single-cell resolution to establish the importance and function of peroxisomes in developmental hematopoiesis. We report that hematopoietic defects are a feature in a severe PBD murine model. Finally, we identify a role for peroxisomes in the regulation of the major histocompatibility class II expression and antigen presentation to CD4+ T cells in dendritic cells. This study adds to our understanding of the mechanisms of PBDs and expands our knowledge of the role of peroxisomes in immunometabolism.