title: Frequency and phenotype of patients carrying TPM2 and TPM3 gene mutations in a cohort of 94 patients with congenital myopathy.
abstract: Congenital myopathies are difficult to classify correctly through molecular testing due to the size and heterogeneity of the genes involved. Therefore, the prevalence of the various genetic causes of congenital myopathies is largely unknown. In our cohort of 94 patients with congenital myopathy, two related female patients and two sporadic, male patients were found to carry mutations in the tropomyosin 2 (TPM2) and tropomyosin 3 (TPM3) genes, respectively. This indicates a low (4.3%) frequency of TPM2 and TPM3 mutations as a cause of congenital myopathy. Compared to previously described patients carrying the same mutations as found in our study (c.503G>A, and c.502C>T in TPM3, and c.415_417delGAG in TPM2), clinical presentation and muscle morphological findings differed in our patients. Differences included variation in distribution of muscle weakness, presence of scoliosis and ptosis, physical performance and joint contractures. The variation in clinical profiles emphasizes the phenotypic heterogeneity. However, common features were also present, such as onset of symptoms in infancy or childhood, musculoskeletal deformities and normal or low plasma levels of creatine kinase. One patient had nemaline myopathy and fiber size disproportion, while three patients had congenital fiber type disproportion (CFTD) on muscle biopsies. TPM2-related CFTD has only been described in two cases, indicating that mutations in TPM2 are rare causes of CFTD.
authors: Neuromuscular Research Unit, Department of Neurology, University Hospital Rigshospitalet, Copenhagen, Denmark.
authors: Gülsenay
authors: G
authors: Citirak
authors: Neuromuscular Research Unit, Department of Neurology, University Hospital Rigshospitalet, Copenhagen, Denmark.
authors: Nanna
authors: N
authors: Witting
authors: Department of Clinical Genetics, University Hospital Rigshospitalet, Copenhagen, Denmark.
authors: Morten
authors: M
authors: Duno
authors: The Danish National Rehabilitation Center for Neuromuscular Diseases, Aarhus, Denmark.
authors: Ulla
authors: U
authors: Werlauff
authors: Department of Cardiology, University Hospital Rigshospitalet, Copenhagen, Denmark.
authors: Helle
authors: H
authors: Petri
authors: Neuromuscular Research Unit, Department of Neurology, University Hospital Rigshospitalet, Copenhagen, Denmark. Electronic address: vissing@rh.dk.
authors: John
authors: J
authors: Vissing
mesh_terms: D000328:Adult; D015331:Cohort Studies; D004252:DNA Mutational Analysis; D005260:Female; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000473:pathology / Q000503:physiopathology; D009154:Mutation; D009224:Myotonia Congenita / Q000453:epidemiology* / Q000235:genetics* / Q000473:pathology / Q000503:physiopathology; D010641:Phenotype; D014335:Tropomyosin / Q000235:genetics*; D055815:Young Adult
chemical_list: C518659:TPM2 protein, human; C498783:TPM3 protein, human; D014335:Tropomyosin
keywords: Congenital fiber type disproportion; Congenital myopathy; Nemaline myopathy; TPM2; TPM3