title: Study of the prevalence of familial autoimmune myasthenia gravis in a Spanish cohort.
abstract: BACKGROUND
  Myasthenia gravis (MG) is an autoimmune disease caused by a failure of neuromuscular transmission. Familial clustering has been reported despiteMG usually manifesting as a sporadic condition presumed not to be inherited. Our study investigated the prevalence of FAMG in a Spanish cohort, characterizing their phenotype,antibody titres and thymus findings.
  
  
  METHODS
  We investigated the presence of familial cases in 462 MG patients, characterizing by age and MGFA class at debut, quantitative MG score, antibody titres, MGFA post-intervention status and thymus pathology.
  
  
  RESULTS
  Sixteen cases from8 unrelated pedigrees were identified. The prevalence of FAMG caseswas 3.46%.Mean age at onset was 57.8 ± 17.4 years (range=23–82). Distribution at debut was: 6 ocular, 4 IIa, 4IIb, 1 IIIa and 1 IIIb. Thymoma was identified in two of the 7 thymectomized individuals.
  
  
  CONCLUSIONS
  The prevalence of FAMG in Spain is similar to other populations. Post-intervention status did not differ from sporadic autoimmune MG. As in other neuromuscular disorders, phenotype and inheritance heterogeneity are present in FAMG. In addition to the interfamilial heterogeneity observed, members of the same family affected with FAMG may even present different ages of onset, severity and thymus involvement. Further studies are necessary to clarify the role of genetic risk factors in this form of autoimmune MG.
authors.affiliation: Myasthenia Gravis Unit, Clinic of Neuromuscular Disorders and Rare Diseases, Neurology Department, Hospital Universitari Vall d'Hebron, Vall d'Hebron Research Institute, Departament de Medicina, Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: Maria
authors.initials: M
authors.lastname: Salvado
authors.affiliation: Myasthenia Gravis Unit, Clinic of Neuromuscular Disorders and Rare Diseases, Neurology Department, Hospital Universitari Vall d'Hebron, Vall d'Hebron Research Institute, Departament de Medicina, Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: Merce
authors.initials: M
authors.lastname: Canela
authors.affiliation: Myasthenia Gravis Unit, Clinic of Neuromuscular Disorders and Rare Diseases, Neurology Department, Hospital Universitari Vall d'Hebron, Vall d'Hebron Research Institute, Departament de Medicina, Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: Jose Maria
authors.initials: JM
authors.lastname: Ponseti
authors.affiliation: Myasthenia Gravis Unit, Clinic of Neuromuscular Disorders and Rare Diseases, Neurology Department, Hospital Universitari Vall d'Hebron, Vall d'Hebron Research Institute, Departament de Medicina, Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Lorenzo
authors.affiliation: Myasthenia Gravis Unit, Clinic of Neuromuscular Disorders and Rare Diseases, Neurology Department, Hospital Universitari Vall d'Hebron, Vall d'Hebron Research Institute, Departament de Medicina, Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Garcia
authors.affiliation: Myasthenia Gravis Unit, Clinic of Neuromuscular Disorders and Rare Diseases, Neurology Department, Hospital Universitari Vall d'Hebron, Vall d'Hebron Research Institute, Departament de Medicina, Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: Sonia
authors.initials: S
authors.lastname: Cazorla
authors.affiliation: Myasthenia Gravis Unit, Clinic of Neuromuscular Disorders and Rare Diseases, Neurology Department, Hospital Universitari Vall d'Hebron, Vall d'Hebron Research Institute, Departament de Medicina, Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: Gisela
authors.initials: G
authors.lastname: Gili
authors.affiliation: Myasthenia Gravis Unit, Clinic of Neuromuscular Disorders and Rare Diseases, Neurology Department, Hospital Universitari Vall d'Hebron, Vall d'Hebron Research Institute, Departament de Medicina, Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: Nuria
authors.initials: N
authors.lastname: Raguer
authors.affiliation: Myasthenia Gravis Unit, Clinic of Neuromuscular Disorders and Rare Diseases, Neurology Department, Hospital Universitari Vall d'Hebron, Vall d'Hebron Research Institute, Departament de Medicina, Universitat Autònoma de Barcelona, Barcelona, Spain. Electronic address: josepgamez.bcn@gmail.com.
authors.forename: Josep
authors.initials: J
authors.lastname: Gamez
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001323:Autoantibodies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009157:Myasthenia Gravis / Q000453:epidemiology* / Q000276:immunology; D010641:Phenotype; D015995:Prevalence; D013030:Spain / Q000453:epidemiology; D055815:Young Adult
chemical_list: D001323:Autoantibodies
keywords: Autoimmunity; Clinical heterogeneity; Dominantly inherited myasthenia gravis; Epidemiology; FAMG; Familial autoimmune myasthenia gravis; Familial occurrence of autoimmune myasthenia gravis; Genetic; Genetic predisposition; Myasthenia gravis; Neuromuscular junction; Thymoma; Twins