Lookup NU author(s): Dr Katherine Johnson,
Dr Ana Topf,
Professor Volker Straub
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© 2020 The Authors. Human Mutation published by Wiley Periodicals LLCFilamin C (encoded by the FLNC gene) is a large actin-cross-linking protein involved in shaping the actin cytoskeleton in response to signaling events both at the sarcolemma and at myofibrillar Z-discs of cross-striated muscle cells. Multiple mutations in FLNC are associated with myofibrillar myopathies of autosomal-dominant inheritance. Here, we describe for the first time a boy with congenital onset of generalized muscular hypotonia and muscular weakness, delayed motor development but no cardiac involvement associated with a homozygous FLNC mutation c.1325C>G (p.Pro442Arg). We performed ultramorphological, proteomic, and functional investigations as well as immunological studies of known marker proteins for dominant filaminopathies. We show that the mutant protein is expressed in similar quantities as the wild-type variant in control skeletal muscle fibers. The proteomic signature of quadriceps muscle is altered and ultrastructural perturbations are evident. Moreover, filaminopathy marker proteins are comparable both in our homozygous and a dominant control case (c.5161delG). Biochemical investigations demonstrate that the recombinant mutant protein is less stable and more prone to degradation by proteolytic enzymes than the wild-type variant. The unusual congenital presentation of the disease clearly demonstrates that homozygosity for mutations in FLNC severely aggravates the phenotype.
Author(s): Kolbel H, Roos A, van der Ven PFM, Evangelista T, Nolte K, Johnson K, Topf A, Wilson M, Kress W, Sickmann A, Straub V, Kollipara L, Weis J, Furst DO, Schara U
Publication type: Article
Publication status: Published
Journal: Human Mutation
Pages: epub ahead of print
Print publication date: 11/07/2020
Online publication date: 09/06/2020
Acceptance date: 07/06/2020
ISSN (print): 1059-7794
ISSN (electronic): 1098-1004
Publisher: John Wiley and Sons Inc.
PubMed id: 32516863
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