Dataset Information

Loss-of-Function Mutations in LGI4, a Secreted Ligand Involved in Schwann Cell Myelination, Are Responsible for Arthrogryposis Multiplex Congenita.

ABSTRACT: Arthrogryposis multiplex congenita (AMC) is a developmental condition characterized by multiple joint contractures resulting from reduced or absent fetal movements. Through genetic mapping of disease loci and whole-exome sequencing in four unrelated multiplex families presenting with severe AMC, we identified biallelic loss-of-function mutations in LGI4 (leucine-rich glioma-inactivated 4). LGI4 is a ligand secreted by Schwann cells that regulates peripheral nerve myelination via its cognate receptor ADAM22 expressed by neurons. Immunolabeling experiments and transmission electron microscopy of the sciatic nerve from one of the affected individuals revealed a lack of myelin. Functional tests using affected individual-derived iPSCs showed that these germline mutations caused aberrant splicing of the endogenous LGI4 transcript and in a cell-based assay impaired the secretion of truncated LGI4 protein. This is consistent with previous studies reporting arthrogryposis in Lgi4-deficient mice due to peripheral hypomyelination. This study adds to the recent reports implicating defective axoglial function as a key cause of AMC.

SUBMITTER: Xue S

PROVIDER: S-EPMC5384038 | biostudies-literature | 2017 Apr

REPOSITORIES: biostudies-literature

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Loss-of-Function Mutations in LGI4, a Secreted Ligand Involved in Schwann Cell Myelination, Are Responsible for Arthrogryposis Multiplex Congenita.

Xue Shifeng S Maluenda Jérôme J Marguet Florent F Shboul Mohammad M Quevarec Loïc L Bonnard Carine C Ng Alvin Yu Jin AY Tohari Sumanty S Tan Thong Teck TT Kong Mung Kei MK Monaghan Kristin G KG Cho Megan T MT Siskind Carly E CE Sampson Jacinda B JB Rocha Carolina Tesi CT Alkazaleh Fawaz F Gonzales Marie M Rigonnot Luc L Whalen Sandra S Gut Marta M Gut Ivo I Bucourt Martine M Venkatesh Byrappa B Laquerrière Annie A Reversade Bruno B Melki Judith J

American journal of human genetics 20170316 4

Arthrogryposis multiplex congenita (AMC) is a developmental condition characterized by multiple joint contractures resulting from reduced or absent fetal movements. Through genetic mapping of disease loci and whole-exome sequencing in four unrelated multiplex families presenting with severe AMC, we identified biallelic loss-of-function mutations in LGI4 (leucine-rich glioma-inactivated 4). LGI4 is a ligand secreted by Schwann cells that regulates peripheral nerve myelination via its cognate rece ...[more]

PMID: 28318499

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Project description:BackgroundBovine arthrogryposis multiplex congenita (AMC) is a syndromic term for a congenital condition characterized by multiple joint contractures. Rare inherited forms of bovine AMC have been reported in different breeds. For AMC in Angus cattle a causative genomic deletion encompassing the agrin (AGRN) gene, encoding an essential neural regulator that induces the aggregation of acetylcholine receptors (AChRs), is known. In 2015, three genetically related cases of generalized AMC affecting Red dairy calves were diagnosed in Denmark.ResultsThe family history of three affected calves suggested an autosomal recessive inheritance. Single nucleotide polymorphism (SNP) genotyping showed a single genomic region of extended homozygosity of 21.5 Mb on chromosome 19. Linkage analysis revealed a maximal parametric LOD score of 1.8 at this region. By whole genome re-sequencing of the three cases, two private homozygous non-synonymous variants were detected in the critical interval. Both variants, located in the myosin phosphatase Rho interacting protein (MPRIP) and the cholinergic receptor nicotinic beta 1 subunit gene (CHRNB1), were perfectly associated with the AMC phenotype. Previously described CHRNB1 variants in humans lead to a congenital myasthenic syndrome with impaired neuromuscular transmission. The cattle variant represents a single base deletion in the first exon of CHRNB1 (c.55delG) introducing a premature stop codon (p.Ala19Profs47*) in the second exon, truncating 96 % of the protein.ConclusionsThis study provides the first phenotypically and genetically characterized example of a bovine AMC phenotype that represents an inherited neuromuscular disorder corresponding to human congenital myasthenic syndrome. The identified CHRNB1 loss of function variant is predicted to have a deleterious effect on fetal AChR function, which could explain the lethal phenotype reported in this study. The identification of this candidate causative mutation thus widens the known phenotypic spectrum of CHRNB1 mutations and enables selection against this pathogenic variant in Red dairy cattle.

Project description:IntroductionArthrogryposis multiplex congenita (AMC) is an umbrella term including hundreds of conditions with the common clinical manifestation of multiple congenital contractures. AMC affects 1 in 3000 live births and is caused by lack of movement in utero. To understand the long-term needs of individuals diagnosed with a rare condition, it is essential to know the prevalence, aetiology and functional outcomes in a large sample. The development and implementation of a multicentre registry is critical to gather this data. This registry aims to improve health through genetic and outcomes research, and ultimately identify new therapeutic targets and diagnostics for treating children with AMC.Methods and analysisParticipants for the AMC registry will be recruited from seven orthopaedic hospitals in North America. Enrollment occurs in two phases; Part 1 focuses on epidemiology, aetiology and interventions. For this part, retrospective and cross-sectional data will be collected using a combination of patient-reported outcomes and clinical measures. Part 2 focuses on core subset of the study team, including a geneticist and bioinformatician, identifying causative genes and linking the phenotype to genotype via whole genome sequencing to identify genetic variants and correlating these findings with pedigree, photographs and clinical information. Descriptive analyses on the sample of 400 participants and logistic regression models to evaluate relationships between outcomes will be conducted.Ethics and disseminationEthical approval has been granted from corresponding governing bodies in North America. Dissemination of findings will occur via traditional platforms (conferences, manuscripts) for the scientific community. Other modalities will be employed to ensure that all stakeholders, including youth, families and patient support groups, may be provided with findings derived from the registry. Ensuring the findings are circulated to a maximum amount of interested parties will ensure that the registry can continue to serve as a platform for hypothesis-driven research and further advancement for AMC.

Project description:IntroductionArthrogryposis multiplex congenita (AMC) describes a heterogeneous group of conditions with multiple congenital contractures. These conditions may be attributed to genetic or other factors inducing decreased fetal movements, including maternal and paternal factors. Discovering the underlying genetic pathways has important repercussions for prevention, gene therapy and genetic counselling. The current literature mainly consists of small-scale, single-site studies, limiting comparability and pooling of findings across individual studies. A pilot registry for children presenting with AMC is proposed to provide the framework for a large-scale AMC registry. This registry will provide the platform to support high-quality studies to inform the distribution, clinical practice and genetics contributing to this group of conditions.Methods and analysisThe registry will be piloted on 40 families of children from birth to 21 years of age presenting with AMC. Data will be collected on the child (demographic and newborn variables), mother and father (demographic, lifestyle habits and medical history). To promote standardised data collection, a manual of operations will be developed. Descriptive statistics will be used to summarise relevant data, regression analyses will be used to explore associations to generate hypotheses regarding factors contributing to AMC. Qualitative analysis will also be used to better describe the various phenotypes.Ethics and disseminationEthics approval was obtained at the participating sites. The pilot registry will provide the platform for multisite AMC registry that will generate multiple research avenues to enhance current care and establish new therapies. Following this pilot study, the participant selection criteria will be refined and datasets will be expanded to include rehabilitation and surgical interventions, and genetic sequencing. The best timing for the questionnaire administration and frequency of follow-up prior to the implementation of a multisite AMC registry will be determined.

Dataset Information

Loss-of-Function Mutations in LGI4, a Secreted Ligand Involved in Schwann Cell Myelination, Are Responsible for Arthrogryposis Multiplex Congenita.

Publications

Loss-of-Function Mutations in LGI4, a Secreted Ligand Involved in Schwann Cell Myelination, Are Responsible for Arthrogryposis Multiplex Congenita.

Similar Datasets

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