Functional prediction of the potential NGLY1 mutations associated with rare disease CDG
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SUBMITTER: Yuan S
PROVIDER: S-EPMC11016977 | biostudies-literature | 2024 Apr
REPOSITORIES: biostudies-literature
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Project description:Pathogenic mutations in DPAGT1 are manifested as two possible phenotypes: congenital disorder of glycosylation DPAGT1-CDG (also known as CDG-Ij), and limb-girdle congenital myasthenic syndrome (CMS) with tubular aggregates. UDP-N-acetylglucosamine-dolichyl-phosphate N-acetylglucosamine phosphotransferase (GPT), the protein encoded by DPAGT1, is an endoplasmic reticulum (ER)-resident protein involved in an initial step in the N-glycosylation pathway. The aim of the present study was to examine the effect of six variants in DPAGT1 detected in patients with DPAGT1-CDG, and the role of endoplasmic reticulum stress, as part of the search for therapeutic strategies to use against DPAGT1-CDG. The effect of the six mutations, i.e., c.358C>A (p.Leu120Met), c.791T>G (p.Val264Gly), c.901C>T (p.Arg301Cys), c.902G>A (p.Arg301His), c.1154T>G (p.Leu385Arg), and of the novel mutation c.329T>C (p.Phe110Ser), were examined via the analysis of DPAGT1 transcriptional profiles and GTP levels in patient-derived fibroblasts. In addition, the transient expression of different mutations was analysed in COS-7 cells. The results obtained, together with those of bioinformatic studies, revealed these mutations to affect the splicing process, the stability of GTP, or the ability of this protein to correctly localise in the ER membrane. The unfolded protein response (UPR; the response to ER stress) was found not to be active in patient-derived fibroblasts, unlike that seen in cells from patients with PMM2-CDG or DPM1-CDG. Even so, the fibroblasts of patients with DPAGT1-CDG seemed to be more sensitive to the stressor tunicamycin. The present work improves our knowledge of DPAGT1-CDG and provides bases for developing tailored splicing and folding therapies.
| S-EPMC5491010 | biostudies-literature
Project description:Pathogenic variants in the NGLY1 gene are associated with a Congenital Disorder of Deglycosylation (CDDG) characterized by delays in reaching developmental milestones, complex hyperkinetic movement disorder, transient elevation of transaminases, and alacrima or hypolacrima. To date, only few cases of NGLY1 deficiency have been identified and reported in the literature. This report highlights a first child of non-consanguineous parents with no relevant family history who presented with hypotonia and poor weight gain since birth. At 2 months, the child developed paroxysmal cervical dystonia, posteriorly resolving spontaneously by age of 3. Subsequently, delays in reaching developmental milestones, ataxia, dyskinesia, visual impairment due to cone rod retinal dystrophy, low triglycerides, and persistently elevated liver transaminases were observed. Extensive etiological investigation was performed, including array-CGH and metabolic evaluation with no abnormalities to note. Trio whole exome analysis identified a homozygous pathogenic variant of the NGLY1 gene, c.1891del (p.Gln631Serfs*7), consistent with CDDG. Both parents were confirmed to be heterozygous carriers. The authors discuss in this case, the clinical presentation, the diagnostic challenges, and review other relevant NGLY1 deficiency cases previously reported in the literature. This case, along with the previous reported in the literature, indicates that pathogenic variants in NGLY1 cause a recognizable phenotype and should be considered in patients with a typical presentation. It also suggests that decreased sweating is not present universally in these patients.
| S-EPMC7203651 | biostudies-literature
Project description:DPAGT1-CDG is a Congenital Disorder of Glycosylation (CDG) that lacks effective therapies. It is caused by mutations in the gene DPAGT1 which encodes the first enzyme in N-linked glycosylation. We used a Drosophila rough eye model of DPAGT1-CDG with an improperly developed, small eye phenotype. We performed a drug repurposing screen on this model using 1,520 small molecules that are 98% FDA/EMA-approved to find drugs that improved its eye. We identified 42 candidate drugs that improved the DPAGT1-CDG model. Notably from this screen, we found that pharmacological and genetic inhibition of the dopamine D2 receptor partially rescued the DPAGT1-CDG model. Loss of both dopamine synthesis and recycling partially rescued the model, suggesting that dopaminergic flux and subsequent binding to D2 receptors is detrimental under DPAGT1 deficiency. This links dopamine signaling to N-glycosylation and represents a new potential therapeutic target for treating DPAGT1-CDG. We also genetically validate other top drug categories including acetylcholine-related drugs, COX inhibitors, and an inhibitor of NKCC1. These drugs and subsequent analyses reveal novel biology in DPAGT1 mechanisms, and they may represent new therapeutic options for DPAGT1-CDG.
| S-EPMC11542785 | biostudies-literature
Project description:PurposeThe endoplasmic reticulum-associated degradation pathway is responsible for the translocation of misfolded proteins across the endoplasmic reticulum membrane into the cytosol for subsequent degradation by the proteasome. To define the phenotype associated with a novel inherited disorder of cytosolic endoplasmic reticulum-associated degradation pathway dysfunction, we studied a series of eight patients with deficiency of N-glycanase 1.MethodsWhole-genome, whole-exome, or standard Sanger sequencing techniques were employed. Retrospective chart reviews were performed in order to obtain clinical data.ResultsAll patients had global developmental delay, a movement disorder, and hypotonia. Other common findings included hypolacrima or alacrima (7/8), elevated liver transaminases (6/7), microcephaly (6/8), diminished reflexes (6/8), hepatocyte cytoplasmic storage material or vacuolization (5/6), and seizures (4/8). The nonsense mutation c.1201A>T (p.R401X) was the most common deleterious allele.ConclusionNGLY1 deficiency is a novel autosomal recessive disorder of the endoplasmic reticulum-associated degradation pathway associated with neurological dysfunction, abnormal tear production, and liver disease. The majority of patients detected to date carry a specific nonsense mutation that appears to be associated with severe disease. The phenotypic spectrum is likely to enlarge as cases with a broader range of mutations are detected.
| S-EPMC4243708 | biostudies-literature
Project description:Biallelic mutations in the gene that encodes the enzyme N-glycanase 1 (NGLY1) cause a rare disease with multi-symptomatic features including developmental delay, intellectual disability, neuropathy, and seizures. NGLY1's activity in human neural cells is currently not well understood. To understand how NGLY1 gene loss leads to the specific phenotypes of NGLY1 deficiency, we employed direct conversion of NGLY1 patient-derived induced pluripotent stem cells (iPSCs) to functional cortical neurons. Transcriptomic, proteomic, and functional studies of iPSC-derived neurons lacking NGLY1 function revealed several major cellular processes that were altered, including protein aggregate-clearing functionality, mitochondrial homeostasis, and synaptic dysfunctions. These phenotypes were rescued by introduction of a functional NGLY1 gene and were observed in iPSC-derived mature neurons but not astrocytes. Finally, laser capture microscopy followed by mass spectrometry provided detailed characterization of the composition of protein aggregates specific to NGLY1-deficient neurons. Future studies will harness this knowledge for therapeutic development.
| S-EPMC10826878 | biostudies-literature
Project description:BACKGROUND:TMEM199 deficiency was recently shown in four patients to cause liver disease with steatosis, elevated serum transaminases, cholesterol and alkaline phosphatase and abnormal protein glycosylation. There is no information on the long-term outcome in this disorder. RESULTS:We here present three novel patients with TMEM199-CDG. All three patients carried the same set of mutations (c.13-14delTT (p.Ser4Serfs*30) and c.92G > C (p.Arg31Pro), despite only two were related (siblings). One mutation (c.92G > C) was described previously whereas the other was deemed pathogenic due to its early frameshift. Western Blot analysis confirmed a reduced level of TMEM199 protein in patient fibroblasts and all patients showed a similar glycosylation defect. The patients presented with a very similar clinical and biochemical phenotype to the initial publication, confirming that TMEM199-CDG is a non-encephalopathic liver disorder. Two of the patients were clinically assessed over two decades without deterioration. CONCLUSION:A rising number of disorders affecting Golgi homeostasis have been published over the last few years. A hallmark finding is deficiency in protein glycosylation, both in N- and O-linked types. Most of these disorders have signs of both liver and brain involvement. However, the present and the four previously reported patients do not show encephalopathy but a chronic, non-progressive (over decades) liver disease with hypertransaminasemia and steatosis. This information is crucial for the patient/families and clinician at diagnosis, as it distinguishes it from other Golgi homeostasis disorders, in having a much more favorable course.
| S-EPMC5763540 | biostudies-literature
Project description:Bipolar disorder (BD) is a common, complex and heritable psychiatric disorder characterized by episodes of severe mood swings. The identification of rare, damaging genomic mutations in families with BD could inform about disease mechanisms and lead to new therapeutic interventions. To determine whether rare, damaging mutations shared identity-by-descent in families with BD could be associated with disease, exome sequencing was performed in multigenerational families of the NIMH BD Family Study followed by in silico functional prediction. Disease association and disease specificity was determined using 5090 exomes from the Sweden-Schizophrenia (SZ) Population-Based Case-Control Exome Sequencing study. We identified 14 rare and likely deleterious mutations in 14 genes that were shared identity-by-descent among affected family members. The variants were associated with BD (P<0.05 after Bonferroni's correction) and disease specificity was supported by the absence of the mutations in patients with SZ. In addition, we found rare, functional mutations in known causal genes for neuropsychiatric disorders including holoprosencephaly and epilepsy. Our results demonstrate that exome sequencing in multigenerational families with BD is effective in identifying rare genomic variants of potential clinical relevance and also disease modifiers related to coexisting medical conditions. Replication of our results and experimental validation are required before disease causation could be assumed.
| S-EPMC5388596 | biostudies-literature
Project description:NGLY1 deficiency is the first recognized autosomal recessive disorder of N-linked deglycosylation (NGLY1-CDDG). This severe multisystemic disease is still poorly known and, to date, most cases have been diagnosed through whole exome or genome sequencing. The aim of this study is to provide the clinical, biochemical and molecular description of the first NGLY1-CDDG patient from France along with a literature review. The index case presented with developmental delay, acquired microcephaly, hypotonia, alacrimia, feeding difficulty, and dysmorphic features. Given the complex clinical picture and the multisystemic involvement, a trio-based exome sequencing was conducted and urine oligosaccharides were assessed using mass spectrometry. The exome sequencing revealed a novel variant in the NGLY1 gene in a homozygous state. NGLY1 deficiency was confirmed by the identification of the Neu5Ac1Hex1GlcNAc1-Asn oligosaccharide in the urine of the patient. Literature review revealed the association of some key clinical and biological features such as global developmental delay-hypertransaminasemia, movement disorders, feeding difficulties and alacrima/hypolacrima.
| S-EPMC7996810 | biostudies-literature
Project description:Biallelic mutations in the gene that encodes the enzyme N-glycanase 1 (NGLY1) cause a rare disease with multi-symptomatic features including developmental delay, intellectual disability, neuropathy and seizures. NGLY1’s activity in human neural cells is currently not well understood. To understand how NGLY1 gene loss leads to the specific phenotypes of NGLY1 deficiency, we employed direct conversion of NGLY1 patient-derived induced pluripotent stem cells (iPSCs) to functional cortical neurons. Transcriptomic, proteomic, and functional studies of iPSC-derived neurons lacking NGLY1 function revealed several major cellular processes that were altered, including protein aggregate-clearing functionality, mitochondrial homeostasis, and synaptic dysfunctions. These phenotypes were rescued by introduction of a functional NGLY1 gene and were observed in iPSC-derived mature neurons, but not astrocytes. Finally, laser capture microscopy followed by mass spectrometry provided detailed characterization of the composition of protein aggregates specific to NGLY1-deficient neurons. Future studies will harness this knowledge for therapeutic development.
2025-02-13 | GSE197454 | GEO
Project description:BackgroundA causal genetic mutation is found in 40% of families with dilated cardiomyopathy (DCM), leaving a large percentage of families genetically unsolved. This prevents adequate counseling and clear recommendations in these families. We aim to identify novel genes or modifiers associated with DCM.MethodsWe performed computational ranking of human genes based on coexpression with a predefined set of genes known to be associated with DCM, which allowed us to prioritize gene candidates for their likelihood of being involved in DCM. Top candidates will be checked for variants in the available whole-exome sequencing data of 142 DCM patients. RNA was isolated from cardiac biopsies to investigate gene expression.ResultsPDLIM5 was classified as the top candidate. An interesting heterozygous variant (189_190delinsGG) was found in a DCM patient with a known pathogenic truncating TTN-variant. The PDLIM5 loss-of-function (LoF) variant affected all cardiac-specific isoforms of PDLIM5 and no LoF variants were detected in the same region in a control cohort of 26,000 individuals. RNA expression of PDLIM5 and its direct interactors (MYOT, LDB3, and MYOZ2) was increased in cardiac tissue of this patient, indicating a possible compensatory mechanism. The PDLIM5 variant cosegregated with the TTN-variant and the phenotype, leading to a high disease penetrance in this family. A second patient was an infant with a homozygous 10 kb-deletion of exon 2 in PDLIM5 resulting in early-onset cardiac disease, showing the importance of PDLIM5 in cardiac function.ConclusionsHeterozygous PDLIM5 variants are rare and therefore will not have a major contribution in DCM. Although they likely play a role in disease development as this gene plays a major role in contracting cardiomyocytes and homozygous variants lead to early-onset cardiac disease. Other environmental and/or genetic factors are probably necessary to unveil the cardiac phenotype in PDLIM5 mutation carriers.
| S-EPMC7005607 | biostudies-literature