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Neurology. 2013 Oct 1;81(14):1205-14. doi: 10.1212/WNL.0b013e3182a6ca62. Epub 2013 Aug 23.

Recessive truncating titin gene, TTN, mutations presenting as centronuclear myopathy.

Author information

1
From the Division of Genetics and Program in Genomics, The Manton Center for Orphan Disease Research (O.C.-B., P.B.A., K.S.-A., E.T.D., L.C.S., K.M., A.H.B.), and Division of Newborn Medicine (P.B.A.), Boston Children's Hospital, Harvard Medical School, Boston, MA; Department of Physiology and Sarver Molecular Cardiovascular Research Program (C.H., H.G.), University of Arizona, Tucson; Center for Computational Molecular Biology and Department of Molecular and Cellular Biology and Biochemistry (R.S., W.G.F.), Brown University, Providence, RI; Department of Translational Medicine (N.V., J.L.), IGBMC, INSERM U964, CNRS UMR7104, University of Strasbourg, Illkirch, France; Departments of Pediatrics and Neurology and Neurotherapeutics (S.T.I.), University of Texas Southwestern Medical Center, Dallas; Department of Neurology (P.B.S.), University of California, Los Angeles; Division of Human Genetics (N.S.), Department of Pediatrics, Rhode Island Hospital, Providence; Department of Pediatrics, Division of Pediatric Pathology (J.M.D.), and Department of Pathology and Laboratory Medicine (M.W.L), Medical College of Wisconsin, Milwaukee; Hasbro Children's Hospital (J.M.D.), and Center for Biomedical Engineering (W.G.F.), Brown University, Providence, RI.

Abstract

OBJECTIVE:

To identify causative genes for centronuclear myopathies (CNM), a heterogeneous group of rare inherited muscle disorders that often present in infancy or early life with weakness and hypotonia, using next-generation sequencing of whole exomes and genomes.

METHODS:

Whole-exome or -genome sequencing was performed in a cohort of 29 unrelated patients with clinicopathologic diagnoses of CNM or related myopathy depleted for cases with mutations of MTM1, DNM2, and BIN1. Immunofluorescence analyses on muscle biopsies, splicing assays, and gel electrophoresis of patient muscle proteins were performed to determine the molecular consequences of mutations of interest.

RESULTS:

Autosomal recessive compound heterozygous truncating mutations of the titin gene, TTN, were identified in 5 individuals. Biochemical analyses demonstrated increased titin degradation and truncated titin proteins in patient muscles, establishing the impact of the mutations.

CONCLUSIONS:

Our study identifies truncating TTN mutations as a cause of congenital myopathy that is reported as CNM. Unlike the classic CNM genes that are all involved in excitation-contraction coupling at the triad, TTN encodes the giant sarcomeric protein titin, which forms a myofibrillar backbone for the components of the contractile machinery. This study expands the phenotypic spectrum associated with TTN mutations and indicates that TTN mutation analysis should be considered in cases of possible CNM without mutations in the classic CNM genes.

PMID:
23975875
PMCID:
PMC3795603
DOI:
10.1212/WNL.0b013e3182a6ca62
[Indexed for MEDLINE]
Free PMC Article
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