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.

[Zellweger syndrome caused by PEX6 gene variation in 2 cases and literature review].

Objective: To summarize the clinical features and genetic characteristics of Zellweger spectrum disorder caused by PEX6 gene variation. Methods: This was a case series research. Clinical date and genetic results of 2 neonatal cases of Zellweger syndrome caused by PEX6 gene variation in Wuhan Children's Hospital, Tongji Medical College, Huazhong University of Science & Technology and Affiliated Hospital of Guangdong Medical University from July 2021 to July 2022 were retrospectively collected and analyzed. Literature up to August 2023 was searched from electronic databases of China National Knowledge Infrastructure (CNKI), Wanfang Data and PubMed with the combined keywords of "Zellweger syndrome" "Zellweger spectrum disorder", and "PEX6 gene" both in Chinese and English. The main clinical features and genetic characteristics of Zellweger spectrum disorder caused by PEX6 gene variation were summarized. Results: The 2 male neonates both developed clinical manifestations as dyspnea, hypotonia, feeding difficulties, enlarged fontanelle, and high palatine arch after birth. Biochemical parameters indicated elevated bile acids, and the cranial ultrasound showed the enlarged bilateral ventricles and subependymal cyst in both 2 neonates. Zellweger syndrome was confirmed by whole exome sequencing, and the results revealed PEX6 gene variation in the 2 neonates, including compound heterozygous variants c.315G>A and c.2095-3T>G, and homozygous variant c.506_507del. Case 1 was hospitalized for 5 days, and case 2 for 32 days; they both died shortly after being discharged (the specific time is unknown). Literature review found 26 patients, including 2 neonates in this study, with Zellweger spectrum disorder caused by PEX6 gene defect reported in 1 Chinese article and 11 English articles. Clinical features included hearing loss (19 cases), developmental delay (19 cases), vision impairment (19 cases), elevated very long chain fatty acids (17 cases), brain malformations (15 cases), hypotonia (12 cases), hepatic insufficiency (12 cases), distinctive facies (10 cases), and dental impairment (9 cases). Compound heterozygous variations dominated the variation types (15 cases), and the frameshift variations (16 cases) were the main pathogenic variations. Conclusions: Zellweger spectrum disorder should be considered when neonates show hypotonia, feeding difficulty, distinctive facial appearance, brain malformations and failure of hearing screening, or when older children show retinitis pigmentosa, sensorineural hearing loss, amelogenesis imperfecta and developmental delays. Detection of genetic variation in the PEX gene is crucial for definitive diagnosis.

Zellweger Spectrum Disorder: Ophthalmic Findings from a New Natural History Study Cohort and Scoping Literature Review.

PURPOSE: Individuals with Zellweger spectrum disorder (ZSD) manifest a spectrum of clinical phenotypes but almost all have retinal degeneration leading to blindness. The onset, extent, and progression of retinal findings have not been well described. It is crucial to understand the natural history of vision loss in ZSD to define reliable endpoints for future interventional trials. Herein, we describe ophthalmic findings in the largest number of ZSD patients to date. DESIGN: Retrospective review of longitudinal data from medical charts and review of cross-sectional data from the literature. PARTICIPANTS: Sixty-six patients with ZSD in the retrospective cohort and 119 patients reported in the literature, divided into 4 disease phenotypes based on genotype or clinical severity. METHODS: We reviewed ophthalmology records collected from the retrospective cohort (Clinicaltrials.gov NCT01668186) and performed a scoping review of the literature for ophthalmic findings in patients with ZSD. We extracted available ophthalmic data and analyzed by age and disease severity. MAIN OUTCOME MEASURES: Visual acuity (VA), posterior and anterior segment descriptions, nystagmus, refraction, electroretinography findings, visual evoked potentials, and OCT results and images. RESULTS: Visual acuity was worse at younger ages in those with severe disease compared with older patients with intermediate to mild disease for all 78 participants analyzed, with a median VA of 0.93 logarithm of the minimum angle of resolution (Snellen 20/320). Longitudinal VA data revealed slow loss over time and legal blindness onset at an average age of 7.8 years. Funduscopy showed retinal pigmentation, macular abnormalities, small or pale optic discs, and attenuated vessels with higher prevalence in milder severity groups and did not change with age. Electroretinography waveforms were diminished in 91% of patients, 46% of which were extinguished and did not change with age. OCT in milder patients revealed schitic changes in 18 of 23 individuals (age range 1.8 to 30 years), with evolution or stable macular edema. CONCLUSIONS: In ZSD, VA slowly deteriorates and is associated with disease severity, serial electroretinography is not useful for documenting vision loss progression, and intraretinal schitic changes may be common. Multiple systematic measures are required to assess retinal dystrophy accurately in ZSD, including functional vision measures. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Novel mutation causing Zellweger syndrome.

Genetic conditions have varied presentations, and one of them is the association with multiple malformation syndrome (MMS), which has a high mortality rate in the immediate postnatal period. Here, we describe a neonate born with multiple anomalies-wide anterior and posterior fontanelle, metopic suture, flat nasal bridge, hypertelorism, low set dysplastic ears, corneal cloudiness, micrognathia, webbed neck, simian crease, undescended testis, hypospadias, congenital talipes equinovarus, hypoplastic inferior cerebellar vermis, poor reflexes, hypotonia and ventricular septal defect. There was a history of sibling death with similar malformations, pointing towards a genetic aetiology. Clinical exome sequencing yielded the diagnosis of Zellweger syndrome with a rare mutation in PEX-19 gene. Inherited metabolic syndromes frequently masquerade as malformations, but family history of an affected sibling and clinical suspicion aided diagnosis of the infant.

[A case of mild Zellweger spectrum disorder first diagnosed as Usher syndrome].

A 5-year-old female patient, presented with"night blindness and poor hearing for 1 year"whose first diagnosis was Usher syndrome due to retinitis pigmentosa accompanied by sensorineural deafness. Compound heterozygous variants (c.5G>A, p.W2*/c.3022C>T, p.P1008S) of PEX1, the causative gene for Zellweger spectrum disorder was confirmed by targeted exome sequencing analysis. Permanent tooth enamel dysplasia, nail leukoplakia, and biochemical abnormalities of peroxisome which is consistent with mild Zellweger spectrum disorder were found when she followed up.

Characterization of Severity in Zellweger Spectrum Disorder by Clinical Findings: A Scoping Review, Meta-Analysis and Medical Chart Review.

Zellweger spectrum disorder (ZSD) is a rare, debilitating genetic disorder of peroxisome biogenesis that affects multiple organ systems and presents with broad clinical heterogeneity. Although severe, intermediate, and mild forms of ZSD have been described, these designations are often arbitrary, presenting difficulty in understanding individual prognosis and treatment effectiveness. The purpose of this study is to conduct a scoping review and meta-analysis of existing literature and a medical chart review to determine if characterization of clinical findings can predict severity in ZSD. Our PubMed search for articles describing severity, clinical findings, and survival in ZSD resulted in 107 studies (representing 307 patients) that were included in the review and meta-analysis. We also collected and analyzed these same parameters from medical records of 136 ZSD individuals from our natural history study. Common clinical findings that were significantly different across severity categories included seizures, hypotonia, reduced mobility, feeding difficulties, renal cysts, adrenal insufficiency, hearing and vision loss, and a shortened lifespan. Our primary data analysis also revealed significant differences across severity categories in failure to thrive, gastroesophageal reflux, bone fractures, global developmental delay, verbal communication difficulties, and cardiac abnormalities. Univariable multinomial logistic modeling analysis of clinical findings and very long chain fatty acid (VLCFA) hexacosanoic acid (C26:0) levels showed that the number of clinical findings present among seizures, abnormal EEG, renal cysts, and cardiac abnormalities, as well as plasma C26:0 fatty acid levels could differentiate severity categories. We report the largest characterization of clinical findings in relation to overall disease severity in ZSD. This information will be useful in determining appropriate outcomes for specific subjects in clinical trials for ZSD.

Quantitative Proteomics and Differential Protein Abundance Analysis after the Depletion of PEX3 from Human Cells Identifies Additional Aspects of Protein Targeting to the ER.

Protein import into the endoplasmic reticulum (ER) is the first step in the biogenesis of around 10,000 different soluble and membrane proteins in humans. It involves the co- or post-translational targeting of precursor polypeptides to the ER, and their subsequent membrane insertion or translocation. So far, three pathways for the ER targeting of precursor polypeptides and four pathways for the ER targeting of mRNAs have been described. Typically, these pathways deliver their substrates to the Sec61 polypeptide-conducting channel in the ER membrane. Next, the precursor polypeptides are inserted into the ER membrane or translocated into the ER lumen, which may involve auxiliary translocation components, such as the TRAP and Sec62/Sec63 complexes, or auxiliary membrane protein insertases, such as EMC and the TMCO1 complex. Recently, the PEX19/PEX3-dependent pathway, which has a well-known function in targeting and inserting various peroxisomal membrane proteins into pre-existent peroxisomal membranes, was also found to act in the targeting and, putatively, insertion of monotopic hairpin proteins into the ER. These either remain in the ER as resident ER membrane proteins, or are pinched off from the ER as components of new lipid droplets. Therefore, the question arose as to whether this pathway may play a more general role in ER protein targeting, i.e., whether it represents a fourth pathway for the ER targeting of precursor polypeptides. Thus, we addressed the client spectrum of the PEX19/PEX3-dependent pathway in both PEX3-depleted HeLa cells and PEX3-deficient Zellweger patient fibroblasts by an established approach which involved the label-free quantitative mass spectrometry of the total proteome of depleted or deficient cells, as well as differential protein abundance analysis. The negatively affected proteins included twelve peroxisomal proteins and two hairpin proteins of the ER, thus confirming two previously identified classes of putative PEX19/PEX3 clients in human cells. Interestingly, fourteen collagen-related proteins with signal peptides or N-terminal transmembrane helices belonging to the secretory pathway were also negatively affected by PEX3 deficiency, which may suggest compromised collagen biogenesis as a hitherto-unknown contributor to organ failures in the respective Zellweger patients.

IMPAIRMENT OF PEROXISOME BIOGENESIS IN THE SPECTRUM OF ZELLWEGER SYNDROME (CLINICAL CASE).

The incidence of rare diseases is approximately two cases per 10,000 people. Today, in most cases, orphan diseases are caused by genetic disorders, less often - some forms of oncological, oncohematological, infectious disorders. These conditions have a severe and chronic course, accompanied by a decrease in quality and a reduction in the life expectancy of patients. Aim - describe a clinical case of an rare disease that is referred to as Zellweger spectrum disorders. Literature review and analysis of clinical-anamnestic and laboratory-instrumental methods of research of a 6.5 years old girl. The given clinical case, namely Zellweger spectrum disorders (ZSD), is a hereditary autosomal recessive disease characterized by nonspecific clinical manifestations and phenotype, which complicates timely diagnosis and delays symptomatic, and in some cases prognostically favorable treatment. Molecular genetic research makes it possible to finally confirm this disease. Therefore, at the slightest suspicion of this pathology, it is worth investigating the level of long-chain fatty acids, plasmalogen of erythrocytes, intermediate metabolites of bile acid synthesis, or carrying out genetic sequencing. Further studies of this condition are carried out in the world in order to obtain new methods of treatment and improve the quality of life of patients. The presented clinical case of a rare disease, which belongs to ZSD, confirms the need for alertness of family doctors and pediatricians in order to timely diagnose and correct rare diseases in children.

Expanded Carrier Screening and the Complexity of Implementation.

Advances in genetic technology have allowed for the development of multiplex panels that can test for hundreds of genetic disorders at the same time; these large panels are referred to as expanded carrier screening. This process can screen couples for far more conditions than the gene-by-gene approach used with traditional carrier screening; however, although expanded carrier screening has been promoted as an efficient means of detecting many more disorders, the complexities of genetic sequencing raise substantial challenges and concerns. In our practice, we have seen a number of complex cases in which only attention to detail on the part of thorough genetic counselors allowed identification of misclassified variants that could have resulted in significant patient harm. We raise issues that require urgent attention by professional societies, including: whether to endorse testing that uses sequencing compared with genotyping; required components of pretest and posttest counseling; reclassification of variants; whether obstetric health care professionals have a responsibility to assure that patients understand the iterative process of variant interpretation and how it relates to carrier screening results; and the question of rescreening in subsequent pregnancies. Implementation of expanded carrier screening needs to be considered thoughtfully in light of the complexity of genetic sequencing and limited knowledge of genetics of most front-line obstetric health care professionals.

Uso de canabidiol como terapia adjuvante em paciente com síndrome de Zellweger: relato de caso / Cannabidiol as adjuvant therapy in a patient with Zellweger syndrome: a case report

RESUMO: Também denominada síndrome cerebrohepatorenal, a síndrome de Zellweger é uma doença autossômica recessiva rara, pertencente ao espectro de erros inatos do metabolismo que afetam os peroxissomos. São causados principalmente por mutações em qualquer um dos 14 genes PEX diferentes que codificam para proteínas envolvidas na montagem do peroxissoma, sendo a mais comum do PEX1. O quadro clínico geralmente é observado no período neonatal e primeira infância, incluindo alterações faciais, hipotonia profunda e ausência de reflexos neonatais, além de disfagia, disfunção hepática e convulsões. O diagnóstico é feito a partir da clínica e testes bioquímicos e confirmados pela visualização da mutação em um dos 14 genes PEX. Como não há tratamento específico, é feito tratamento sintomático. Nosso paciente masculino de 1 ano e 9 meses apresentou a hipotonia congênita como sintoma marcante, além de crises convulsivas recorrentes logo após o nascimento. Evoluiu com necessidade de gastrostomia e estagnação de marcos neuromotores. O diagnóstico foi confirmado aos seis meses, através da dosagem de ácidos graxos de cadeia longa. Crises convulsivas evoluíram de maneira refratária a diversos anticonvulsivantes e com elevada frequência diária, por isso iniciamos canabidiol (CBD-RSHO GOLD) por via enteral que reduziu significantemente as crises. Não há tratamento definitivo para esta enfermidade, sendo importante tratamento sintomático das crises convulsivas e terapias de reabilitação, nesse caso, o uso de (CBD- RSHO GOLD) provocou uma redução de 92% na frequência de crises diárias do paciente. No entanto, não é possível concluir, ainda, melhoras em outros sinais e sintomas. (AU)

ABSTRACT: Also referred to as "brain-liver-kidney" syndrome, the Zellweger syndrome is a rare autosomal recessive disorder, belonging to the spectrum of inborn errors of metabolism that affect peroxisomes. They are caused mainly by mutations in any of the 14 different PEX genes that code for proteins involved in the assembly of peroxisome, being the most common of PEX1. The clinic is usually observed in the neonatal and early childhood period, including facial changes, deep hypotonia, and absence of neonatal reflexes in childhood, in addition to dysphagia, hepatic dysfunction, and seizures. The diagnosis is made from clinical and biochemical tests and confirmed by the visualization of the mutation in one of the 14 PEX genes. Since there is no specific treatment, symptomatic treatment is done. Our 1-year and 9-month-old male patient presented congenital hypotonia as a striking symptom in addition to recurrent seizures shortly after birth. It evolved with the need for gastrostomy and stagnation of neuromotor frames. The diagnosis was confirmed at six months by the measurement of long-chain fatty acids. Convulsive seizures evolved in a manner that was refractory to several anticonvulsants and with a high daily frequency, so we initiated cannabidiol (CBD-RSHO GOLD) by an enteral route that significantly reduced the seizures. Since there is no avail-able treatment for seizures, in this case, the use of CBD-RSHO GOLD reduced by 92% the daily seizure frequency. However, it is not possible to conclude further improvements in other signs and symptoms. (AU)

Insufficiency of ciliary cholesterol in hereditary Zellweger syndrome.

Primary cilia are antenna-like organelles on the surface of most mammalian cells that receive sonic hedgehog (Shh) signaling in embryogenesis and carcinogenesis. Cellular cholesterol functions as a direct activator of a seven-transmembrane oncoprotein called Smoothened (Smo) and thereby induces Smo accumulation on the ciliary membrane where it transduces the Shh signal. However, how cholesterol is supplied to the ciliary membrane remains unclear. Here, we report that peroxisomes are essential for the transport of cholesterol into the ciliary membrane. Zellweger syndrome (ZS) is a peroxisome-deficient hereditary disorder with several ciliopathy-related features and cells from these patients showed a reduced cholesterol level in the ciliary membrane. Reverse genetics approaches revealed that the GTP exchange factor Rabin8, the Rab GTPase Rab10, and the microtubule minus-end-directed kinesin KIFC3 form a peroxisome-associated complex to control the movement of peroxisomes along microtubules, enabling communication between peroxisomes and ciliary pocket membranes. Our findings suggest that insufficient ciliary cholesterol levels may underlie ciliopathies.

Hepatic symptoms and histology in 13 patients with a Zellweger spectrum disorder.

Patients with a Zellweger spectrum disorder (ZSD) have a defect in the assembly or maintenance of peroxisomes, leading to a multisystem disease with variable outcome. Liver disease is an important feature in patients with severe and milder phenotypes and a frequent cause of death. However, the course and histology of liver disease in ZSD patients are ill-defined. We reviewed the hepatic symptoms and histological findings of 13 patients with a ZSD in which one or several liver biopsies have been performed (patient age 0.2-39 years). All patients had at least some histological liver abnormalities, ranging from minor fibrosis to cirrhosis. Five patients demonstrated significant disease progression with liver failure and early death. In others, liver-related symptoms were absent, although some still silently developed cirrhosis. Patients with peroxisomal mosaicism had a better prognosis. In addition, we show that patients are at risk to develop a hepatocellular carcinoma (HCC), as one patient developed a HCC at the age of 36 years and one patient a precancerous lesion at the age of 18 years. Thus, regular examination to detect fibrosis or cirrhosis should be included in the standard care of ZSD patients. In case of advanced fibrosis/cirrhosis expert consultation and HCC screening should be initiated. This study further delineates the spectrum and significance of liver involvement in ZSDs.

Zellweger spectrum disorder patient-derived fibroblasts with the PEX1-Gly843Asp allele recover peroxisome functions in response to flavonoids.

Zellweger spectrum disorder (ZSD) results from biallelic mutations in PEX genes required for peroxisome biogenesis. PEX1-G843D is a common hypomorphic allele in the patient population that is associated with milder disease. In prior work using a PEX1-G843D/null patient fibroblast line expressing a green fluorescent protein (GFP) reporter with a peroxisome-targeting signal (GFP-PTS1), we demonstrated that treatments with the chemical chaperone betaine and flavonoid acacetin diacetate recovered peroxisome functions. To identify more effective compounds for preclinical investigation, we evaluated 54 flavonoids using this cell-based phenotype assay. Diosmetin showed the most promising combination of potency and efficacy (EC50 2.5 µM). All active 5',7'-dihydroxyflavones showed greater average efficacy than their corresponding flavonols, whereas the corresponding flavanones, isoflavones, and chalcones tested were inactive. Additional treatment with the proteostasis regulator bortezomib increased the percentage of import-rescued cells over treatment with flavonoids alone. Cotreatments of diosmetin and betaine showed the most robust additive effects, as confirmed by three independent functional assays in primary PEX1-G843D patient cells, but neither agent was active alone or in combination in patient cells homozygous for the PEX1 c.2097_2098insT null allele. Moreover, diosmetin treatment increased PEX1, PEX6, and PEX5 protein levels in PEX1-G843D patient cells, but none of these proteins increased in PEX1 null cells. We propose that diosmetin acts as a pharmacological chaperone that improves the stability, conformation, and functions of PEX1/PEX6 exportomer complexes required for peroxisome assembly. We suggest that diosmetin, in clinical use for chronic venous disease, and related flavonoids warrant further preclinical investigation for the treatment of PEX1-G843D-associated ZSD.

Histologic and ultrastructural features in early and advanced phases of Zellweger spectrum disorder (infantile Refsum disease).

Zellweger spectrum disorders (ZSD) are rare autosomal recessive inherited metabolic disorders and include severe (Zellweger syndrome) and milder phenotypes [neonatal adrenoleukodystrophy and infantile Refsum disease (IRD)]. ZSD are characterized by impaired peroxisomal functions and lack of peroxisomes detected by electron microscopy (EM). ZSD are caused by mutations in any of the 14 PEX genes. Patients with ZSD commonly demonstrate nonspecific hepatic symptoms within the first year, often without clinical suspicion of ZSD. Thus, recognition of pathologic findings in the liver is critical for the early diagnosis. We herein demonstrate the histologic and ultrastructural features in liver biopsies in the early and advanced phases from a 16-year-old male with IRD. The initial biopsy at 5 months of age showed a lack of peroxisomes by EM, and this finding played a critical role in the early diagnosis. In contrast, the second biopsy at 14 years of age, after long-term diet therapy, demonstrated significant disease progression with near-cirrhotic liver. In addition to lack of peroxisomes, EM revealed abundant trilamellar inclusions within large angulated lysosomes in many of the hepatocytes and Kupffer cells. Mitochondrial abnormalities were identified only in the second biopsy and were mainly identified in damaged cells; thus they were likely nonspecific secondary changes. This is the first report demonstrating histological and ultrastructural features of liver biopsies in the early and advanced phases from a child with ZSD. Trilamellar inclusions are considered to be an ultrastructural hallmark of ZSD, but they may not be apparent in the early phases.

Scimitar-like ossification of patellae led to diagnosis of Zellweger syndrome in newborn: a case report.

Zellweger syndrome is the most severe form of a group of autosomal recessive disorders with defective peroxisomes. We report a case of Zellweger syndrome in a newborn baby, which was first suspected by the presence of scimitar-like patella seen on skeletal survey. The subsequent brain MRI showed germinolytic cysts and polymicrogyria, which furthered the suspicion. Laboratory and genetic results confirmed the diagnosis. To date, there are a limited number of case reports of this rare disease. We emphasize skeletal findings that can lead to targeted genetic and laboratory testing and hence earlier diagnosis.

Novel compound heterozygous mutations in the PEX1 gene in two Chinese newborns with Zellweger syndrome based on whole exome sequencing.

Peroxisome biogenesis disorders (PBDs) represent a spectrum of human genetic disorders that are characterized by damaged peroxisome assembly. In the newborn period, the characteristics of affected patients include dysmorphic facial features, neonatal hypotonia, seizures, ocular abnormalities, poor feeding, liver cysts with hepatic dysfunction and skeletal defects. These can be caused by a defect in at least 14 different PEX genes. In this study, whole-exome sequencing (WES) was performed on samples from two Chinese newborns with clinical features of Zellweger syndrome. WES identified two novel mutations (c.2416+1G>T and c.2489delT) in patient 1 and another two novel mutations (c.1483+1G>A and c.1727dupG) in patient 2 in the PEX1 gene. All four mutations have a serious influence on the protein function, which also highlights the power of WES, particularly in clinically challenging cases.