title: Congenital myopathy with cap-like structures and nemaline rods: case report and literature review.
abstract: BACKGROUND
  Cap myopathy is a rare congenital myopathy characterized by cap structures located at the periphery of the muscle fiber. Cap structures consist of disarranged thin filaments with enlarged Z discs. The clinical presentation and natural history of cap myopathy is variable and overlaps with other congenital myopathies.
  
  
  METHODS
  We describe a 10-year-old boy with cap myopathy and contrast him with 20 other individuals reported in the literature.
  
  
  RESULTS
  Our patient presented at birth with hypotonia and weakness and subsequently developed respiratory failure in infancy. He is ambulatory but has increasing fatigue and requires a wheelchair by midafternoon. His muscle biopsy at 3 months revealed a nemaline myopathy and secondary fiber-type disproportion with type 1 hypotrophy and predominance. A repeat muscle biopsy at age 6 years revealed numerous peripherally located cap-like structures containing nemaline rods and exhibited a spectrum of Z-disk and myofibrillar abnormalities. Molecular genetic testing was performed for NEB, TPM2, TPM3, ACTA1, TNNT1, SEPN1, SMN1, DMPK, FSHMD1A, and mtDNA. A known pathogenic mutation, c.1152+1G>A, and a previously unreported variant, c.1782+4_1782+5delAG, were detected in NEB.
  
  
  CONCLUSIONS
  Our patient has a more severe phenotype than most reported patients and is the first patient with cap myopathy to have a mutation in NEB. Our case supports the identification of cap myopathy as a congenital myopathy with significant overlapping features with nemaline myopathies and further elucidates the phenotype of this disease.
authors: Department of Pediatrics, Queen's University, Kingston, Ontario, Canada. Electronic address: shaleapiteau@hotmail.com.
authors: Shalea J
authors: SJ
authors: Piteau
authors: Department of Pathology and Molecular Medicine, Queen's University and Kingston General Hospital, Kingston, Ontario, Canada.
authors: John P
authors: JP
authors: Rossiter
authors: Department of Pediatrics, Queen's University, Kingston, Ontario, Canada.
authors: R Garth
authors: RG
authors: Smith
authors: Department of Pediatrics, Queen's University, Kingston, Ontario, Canada.
authors: Jennifer J
authors: JJ
authors: MacKenzie
mesh_terms: D002648:Child; D006801:Humans; D008297:Male; D009124:Muscle Proteins / Q000235:genetics*; D017696:Myopathies, Nemaline / Q000235:genetics / Q000473:pathology / Q000503:physiopathology; D020914:Myopathies, Structural, Congenital / Q000235:genetics / Q000473:pathology / Q000503:physiopathology
chemical_list: D009124:Muscle Proteins; C035620:nebulin
keywords: NEB; cap myopathy; case report; literature review; nemaline rods