A novel PEX1 mutation in a Moroccan family with Zellweger spectrum disorders.
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ABSTRACT:
SUBMITTER: Bousfiha A
PROVIDER: S-EPMC5390255 | biostudies-literature | 2017
REPOSITORIES: biostudies-literature
Publications
A novel <i>PEX1</i> mutation in a Moroccan family with Zellweger spectrum disorders.
Bousfiha Amale A Bakhchane Amina A Charoute Hicham H Riahi Zied Z Snoussi Khalid K Rouba Hassan H Bonnet Crystel C Petit Christine C Barakat Abdelhamid A
Human genome variation 20170413
Mutations in the <i>PEX1</i> gene are usually associated with recessive inherited diseases including Zellweger spectrum disorders. In this work, we identified a new pathogenic missense homozygous <i>PEX</i><i>1</i> mutation (p.Leu1026Pro, c.3077T>C) in two Moroccan syndromic deaf siblings from consanguineous parents. This variation is located in the P-loop containing nucleoside triphosphate hydrolase of protein domain and probably causes an alteration in the hydrolysis of ATP. ...[more]
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Project description:Zellweger spectrum disorder (ZSD) is a disease continuum that results from inherited defects in PEX genes essential for normal peroxisome assembly. These autosomal recessive disorders impact brain development and also cause postnatal liver, adrenal, and kidney dysfunction, as well as loss of vision and hearing. The hypomorphic PEX1-G843D missense allele, observed in approximately 30% of ZSD patients, is associated with milder clinical and biochemical phenotypes, with some homozygous individuals surviving into early adulthood. Nonetheless, affected children with the PEX1-G843D allele have intellectual disability, failure to thrive, and significant sensory deficits. To enhance our ability to test candidate therapies that improve human PEX1-G843D function, we created the novel Pex1-G844D knock-in mouse model that represents the murine equivalent of the common human mutation. We show that Pex1-G844D homozygous mice recapitulate many classic features of mild ZSD cases, including growth retardation and fatty livers with cholestasis. In addition, electrophysiology, histology, and gene expression studies provide evidence that these animals develop a retinopathy similar to that observed in human patients, with evidence of cone photoreceptor cell death. Similar to skin fibroblasts obtained from ZSD patients with a PEX1-G843D allele, we demonstrate that murine cells homozygous for the Pex1-G844D allele respond to chaperone-like compounds, which normalizes peroxisomal β-oxidation. Thus, the Pex1-G844D mouse provides a powerful model system for testing candidate therapies that address the most common genetic cause of ZSD. In addition, this murine model will enhance studies focused on mechanisms of pathogenesis.
| S-EPMC4901203 | biostudies-literature
Project description:Gene expression analysis of retinas from a mouse model of the mild form of Zellweger spectrum disorder (ZSD). Mice homozygous for the hypomorphic Pex1-G844D allele, the murine ortholog of the human PEX1-G843D mutation found in a subset of patients with autosomal recessive ZSD, develop phenotypes found in humans with a milder form of ZSD, including retinal degeneration and vision loss. Similar to humans, mice heterozygous for the hypomorphic Pex1-G844D allele do not display age-related retinal abnormalities. We conducted a comparative analysis of retinal gene expression profile from Pex1-G844D homozygous and heterozygous mice in order to investigate the pathomechanisms of vision loss in humans with mild forms of ZSD.
2013-12-15 | GSE52348 | GEO
Project description:OBJECTIVE: To analyse the PEX1 gene, the most common cause for peroxisome biogenesis disorders (PBD), in a consecutive series of patients with Zellweger spectrum. METHODS: Mutations were detected by different methods including SSCP analyses as a screening technique on the basis of genomic or cDNA, followed by direct sequencing of PCR fragments with an abnormal electrophoresis pattern. RESULTS: 33 patients were studied. Two common mutations, c.2528G-->A, G843D and c.2098_2098insT, I700YfsX42, accounted for over 80% of all abnormal PEX1 alleles, emphasising their diagnostic relevance. Most PEX1 mutations were distributed over the two AAA cassettes with the two functional protein domains, D1 and D2, and the highly conserved Walker motifs. Phenotypic severity of Zellweger spectrum in CG1 depended on the effect of the mutation on the PEX1 protein, peroxin 1. PEX1 mutations could be divided into two classes of genotype-phenotype correlation: class I mutations led to residual PEX1 protein levels and function and a milder phenotype; class II mutations almost abolished PEX1 protein levels and function, resulting in a severe phenotype. Compound heterozygote patients for a class I and class II mutation had an intermediate phenotype. CONCLUSIONS: Molecular confirmation of the clinical and biochemical diagnosis will allow the prediction of the clinical course of disease in individual PBD cases.
| S-EPMC1736134 | biostudies-other
Project description:Gene expression analysis of retinas from a mouse model of the mild form of Zellweger spectrum disorder (ZSD). Mice homozygous for the hypomorphic Pex1-G844D allele, the murine ortholog of the human PEX1-G843D mutation found in a subset of patients with autosomal recessive ZSD, develop phenotypes found in humans with a milder form of ZSD, including retinal degeneration and vision loss. Similar to humans, mice heterozygous for the hypomorphic Pex1-G844D allele do not display age-related retinal abnormalities. We conducted a comparative analysis of retinal gene expression profile from Pex1-G844D homozygous and heterozygous mice in order to investigate the pathomechanisms of vision loss in humans with mild forms of ZSD. Whole retinas were obtained from 4 mice homozygous and 4 mice heterozygous for the hypomorphic Pex1-G844D allele, the murine ortholog of the human PEX1-G843D mutation found in a subset of patients with autosomal recessive Zellweger spectrum disorder (ZSD). The former group of animals show abnormal age-related related retinal degeneration due to peroxisome assembly defect resulting from having two copies of the hypomorphic Pex1-G844D allele. The latter group of animals display no evidence of abnormal age-related retinal degeneration due to the presence of one wild type copy of the Pex1 gene. The overall goal was to identify differentially expressed genes between mice homozygous and heterozygous for the hypomorphic Pex1-G844D allele that are informative of the pathomechanisms of age-related retinal degeneration in the former group.
2013-12-15 | E-GEOD-52348 | biostudies-arrayexpress
Project description:PurposePeroxisome biogenesis disorders-Zellweger spectrum disorders (PBD-ZSD) are metabolic diseases with multisystem manifestations. Individuals with PBD-ZSD exhibit impaired peroxisomal biochemical functions and have abnormal levels of peroxisomal metabolites, but the broader metabolic impact of peroxisomal dysfunction and the utility of metabolomic methods is unknown.MethodsWe studied 19 individuals with clinically and molecularly characterized PBD-ZSD. We performed both quantitative peroxisomal biochemical diagnostic studies in parallel with untargeted small molecule metabolomic profiling in plasma samples with detection of >650 named compounds.ResultsThe cohort represented intermediate to mild PBD-ZSD subjects with peroxisomal biochemical alterations on targeted analysis. Untargeted metabolomic profiling of these samples revealed elevations in pipecolic acid and long-chain lysophosphatidylcholines, as well as an unanticipated reduction in multiple sphingomyelin species. These sphingomyelin reductions observed were consistent across the PBD-ZSD samples and were rare in a population of >1,000 clinical samples. Interestingly, the pattern or "PBD-ZSD metabolome" was more pronounced in younger subjects suggesting studies earlier in life reveal larger biochemical changes.ConclusionUntargeted metabolomics is effective in detecting mild to intermediate cases of PBD-ZSD. Surprisingly, dramatic reductions in plasma sphingomyelin are a consistent feature of the PBD-ZSD metabolome. The use of metabolomics in PBD-ZSD can provide insight into novel biomarkers of disease.
| S-EPMC7605708 | biostudies-literature
Project description:IntroductionZellweger spectrum disorders (ZSDs) are characterized by a failure in peroxisome formation, caused by autosomal recessive mutations in different PEX genes. At least some of the progressive and irreversible clinical abnormalities in patients with a ZSD, particularly liver dysfunction, are likely caused by the accumulation of toxic bile acid intermediates. We investigated whether cholic acid supplementation can suppress bile acid synthesis, reduce accumulation of toxic bile acid intermediates and improve liver function in these patients.MethodsAn open label, pretest-posttest design study was conducted including 19 patients with a ZSD. Participants were followed longitudinally during a period of 2.5 years prior to the start of the intervention. Subsequently, all patients received oral cholic acid and were followed during 9 months of treatment. Bile acids, peroxisomal metabolites, liver function and liver stiffness were measured at baseline and 4, 12 and 36 weeks after start of cholic acid treatment.ResultsDuring cholic acid treatment, bile acid synthesis decreased in the majority of patients. Reduced levels of bile acid intermediates were found in plasma and excretion of bile acid intermediates in urine was diminished. In patients with advanced liver disease (n = 4), cholic acid treatment resulted in increased levels of plasma transaminases, bilirubin and cholic acid with only a minor reduction in bile acid intermediates.ConclusionsOral cholic acid therapy can be used in the majority of patients with a ZSD, leading to at least partial suppression of bile acid synthesis. However, caution is needed in patients with advanced liver disease due to possible hepatotoxic effects.
| S-EPMC5065608 | biostudies-literature
Project description:Peroxisomal biogenesis disorders (PBD) are rare autosomal recessive disorders with various degrees of severity caused by hypomorphic mutations in 13 different peroxin (PEX) genes. In this study, we report the clinical and molecular characterization of a 9-years-old female presenting an apparently isolated pre-lingual sensorineural hearing loss (SNHL) and early onset Retinitis Pigmentosa (RP) that may clinically overlap with Usher syndrome. Genetic testing by clinical exome sequencing identified two variants in PEX1: the missense variant c.274G > C; p.(Val92Leu) that was already reported in a PBD patient, and the variant c.2140_2145dup; p.(Ser714_Gln715dup) which is a novel, non-frameshift variant, absent in control databases. On the basis of the molecular analysis, a thorough clinical examination revealed nail and dental abnormalities, a mild cognitive impairment, learning disabilities and poor feeding, apart from the retinal and audiological features initially identified. The clinical and molecular findings led us to the diagnosis of a mild form of PBD. This study further emphasizes that mild forms of PBD can be a differential diagnosis of Usher syndrome and suggests that patients with mild cognitive impairment associated to visual and hearing loss should perform a comprehensive mutation screening that includes PEX genes.
| S-EPMC7306489 | biostudies-literature
Project description:Zellweger spectrum disorders (ZSD) are inborn metabolic diseases cause by genetic alterations in PEX genes leading to peroxisomal biogenesis disorder (PBD). Supportive care is standard since no validated treatment is able to modify the dismal natural history of the disease. Mouse models exist to study ZSD pathophysiology but they are limited by poor survival of the affected pups and breeding restrictions. To overcome these limitations, hypomorphic Pex1 p.G844D allele, equivalent to common mild human PEX1 p.G843D mutation, was backcrossed from C57BL/6N mouse to NMRI background. NMRI ZSD mouse breeding lead autosomal recessive Mendelian inheritance pattern with (median (min-max)) 10 (7-15) pups/mating compared to 4 (2-7) pups/mating in C57BL/6N background (p < 0.0001). We longitudinally phenotyped NMRI ZSD mice at 1, 2, 3 and 6 months of age to render this model suitable for future therapeutic interventions. NMRI ZSD mice exhibited growth retardation despite their higher daily energy intake. Mouse embryonic fibroblasts displayed classical PBD immunofluorescence pattern with peroxisomal mosaicism like milder ZSD patients skin fibroblasts. ZSD mice liver were enlarged and no liver lipid accumulation was detected. Yet, ZSD mouse plasma and liver showed very long-chain fatty acids, oxysterols and C27 bile acids intermediates elevation. Longitudinal study depicted trend to normalization for C26 and phytanic acid as it was shown for some ZSD patients reaching adulthood. ZSD mouse liver glycogen content was drastically reduced and liver RNA-Seq analysis confirmed glycogen metabolism genes downregulation. In conclusion, NMRI ZSD mouse model is suitable for ZSD liver-targeted therapies evaluation.
2020-02-20 | GSE145524 | GEO
Project description:Zellweger spectrum disorders (ZSDs) represent the major subgroup within the peroxisomal biogenesis disorders caused by defects in PEX genes. The Zellweger spectrum is a clinical and biochemical continuum which can roughly be divided into three clinical phenotypes. Patients can present in the neonatal period with severe symptoms or later in life during adolescence or adulthood with only minor features. A defect of functional peroxisomes results in several metabolic abnormalities, which in most cases can be detected in blood and urine. There is currently no curative therapy, but supportive care is available. This review focuses on the management of patients with a ZSD and provides recommendations for supportive therapeutic options for all those involved in the care for ZSD patients.
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Project description:Zellweger spectrum disorders (ZSDs), a subgroup of peroxisomal biogenesis disorders, have a generalized defect in peroxisome function. Liver disease in ZSDs has been linked to accumulation of C27-bile acid intermediates due to the lack of peroxisomal ?-oxidation of these intermediates to form primary C24-bile acids. Oral treatment with primary bile acid, cholic acid (CA), inhibits formation of hepatotoxic C27-bile acids by restoring normal physiologic feedback inhibition on bile acid synthesis. We present the long-term CA treatment and liver-related outcomes for 3 pediatric patients with ZSDs who have received CA treatment for ?15 years. Ongoing CA treatment was associated with stabilized liver function, as shown by serum biochemistries and liver histopathology, and no treatment-related adverse effects were observed. All 3 patients have attended regular school with classroom accommodations and attained a good quality of life. Our patient outcomes suggest that early and ongoing CA therapy may sustain liver function in patients with ZSDs.
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