A CADM3 variant causes Charcot-Marie-Tooth disease with marked upper limb involvement

The CADM family of proteins consists of four neuronal specific adhesion molecules (CADM1, CADM2, CADM3 and CADM4) that mediate the direct contact and interaction between axons and glia. In the peripheral nerve, axon-Schwann cell interaction is essential for the structural organization of myelinated fibres and is primarily mediated by the binding of CADM3, expressed in axons, to CADM4, expressed by myelinating Schwann cells. We have identified—by whole exome sequencing—three unrelated families, including one de novo patient, with axonal Charcot-Marie-Tooth disease (CMT2) sharing the same private variant in CADM3, Tyr172Cys. This variant is absent in 230 000 control chromosomes from gnomAD and predicted to be pathogenic. Most CADM3 patients share a similar phenotype consisting of autosomal dominant CMT2 with marked upper limb involvement. High resolution mass spectrometry analysis detected a newly created disulphide bond in the mutant CADM3 potentially modifying the native protein conformation. Our data support a retention of the mutant protein in the endoplasmic reticulum and reduced cell surface expression in vitro. Stochastic optical reconstruction microscopy imaging revealed decreased co-localization of the mutant with CADM4 at intercellular contact sites. Mice carrying the corresponding human mutation (Cadm3Y170C) showed reduced expression of the mutant protein in axons. Cadm3Y170C mice showed normal nerve conduction and myelin morphology, but exhibited abnormal axonal organization, including abnormal distribution of Kv1.2 channels and Caspr along myelinated axons. Our findings indicate the involvement of abnormal axon-glia interaction as a disease-causing mechanism in CMT patients with CADM3 mutations. A correction has been published: Brain, Volume 144, Issue 7, July 2021, Page e64, https://doi.org/10.1093/brain/awab18

Mediterranean chromosome number reports - 23

This is the twenty-three of a series of reports of chromosomes numbers from Mediterranean area, peri-Alpine communities and the Atlantic Islands, in English or French language. It comprises contributions on 56 taxa: Anthriscus, Bupleurum, Dichoropetalum, Eryngium, Ferula, Ferulago, Lagoecia, Oenanthe, Prangos, Scaligeria, Seseli and Torilis from Turkey by Ju. V. Shner, T. V. Alexeeva, M. G. Pimenov & E. V. Kljuykov (Nos 1768-1783); Astrantia, Bupleurum, Daucus, Dichoropetalum, Eryngium, Heracleum, Laserpitium, Melanoselinum, Oreoselinum, Pimpinella, Pteroselinum and Ridolfia from Former Jugoslavia (Slovenia), Morocco and Portugal by J. Shner & M. Pimenov (1784-1798); Arum, Biarum and Eminium from Turkey by E. Akalin, S. Demirci & E. Kaya (1799-1804); Colchicum from Turkey by G. E. Genç, N. Özhatay & E. Kaya (1805-1808); Crocus and Galanthus from Turkey by S. Yüzbaşioglu, S. Demirci & E. Kaya (1809-1812); Pilosella from Italy by E. Di Gristina, G. Domina & A. Geraci (1813-1814); Narcissus from Sicily by A. Troia, A. M. Orlando & R. M. Baldini (1815-1816); Allium, Cerastium, Cochicum, Fritillaria, Narcissus and Thymus from Greece, Kepfallinia by S. Samaropoulou, P. Bareka & G. Kamari (1817-1823)

Erratum: A CADM3 variant causes Charcot-Marie-Tooth disease with marked upper limb involvement (Brain (2021) 144:4 (1197-1213) DOI: 10.1093/brain/awab019)

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A CADM3 variant causes Charcot-Marie-Tooth disease with marked upper limb involvement

The CADM family of proteins consists of four neuronal specific adhesion molecules (CADM1, CADM2, CADM3 and CADM4) that mediate the direct contact and interaction between axons and glia. In the peripheral nerve, axon-Schwann cell interaction is essential for the structural organization of myelinated fibres and is primarily mediated by the binding of CADM3, expressed in axons, to CADM4, expressed by myelinating Schwann cells. We have identified - by whole exome sequencing - three unrelated families, including one de novo patient, with axonal Charcot-Marie-Tooth disease (CMT2) sharing the same private variant in CADM3, Tyr172Cys. This variant is absent in 230 000 control chromosomes from gnomAD and predicted to be pathogenic. Most CADM3 patients share a similar phenotype consisting of autosomal dominant CMT2 with marked upper limb involvement. High resolution mass spectrometry analysis detected a newly created disulphide bond in the mutant CADM3 potentially modifying the native protein conformation. Our data support a retention of the mutant protein in the endoplasmic reticulum and reduced cell surface expression in vitro. Stochastic optical reconstruction microscopy imaging revealed decreased co-localization of the mutant with CADM4 at intercellular contact sites. Mice carrying the corresponding human mutation (Cadm3Y170C) showed reduced expression of the mutant protein in axons. Cadm3Y170C mice showed normal nerve conduction and myelin morphology, but exhibited abnormal axonal organization, including abnormal distribution of Kv1.2 channels and Caspr along myelinated axons. Our findings indicate the involvement of abnormal axon-glia interaction as a disease-causing mechanism in CMT patients with CADM3 mutations

Search for leptoquarks in Z0 decays

General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Received 5 March 1991 We have searched for direct leptoquark production in Z ° decays from a scan of the Z ° resonance, in the energy range 88.2 ~< x/] ~< 94.2 GeV, using 5.2 pb-~ of data. We exclude the existence of scalar leptoquarks with masses less than 41 to 44 GeV, depending on the charge assignments, at the 95% confidence level