title: Milder phenotype in facioscapulohumeral dystrophy with 7-10 residual D4Z4 repeats.
abstract: OBJECTIVE
  To examine the relationship of clinical and genetic features of patients with facioscapulohumeral muscular dystrophy (FSHD) with 7-10 residual D4Z4 repeats in a large genetically defined FSHD1 cohort.
  
  
  METHODS
  We performed a prospective cross-sectional observational study of 74 clinically affected patients with FSHD1. Measures of clinical severity were compared between patients with 1-6 D4Z4 repeats and 7-10 repeats, and included D4Z4 CpG methylation, age at diagnosis, age-adjusted clinical severity score, a muscle pathology grade of quadriceps biopsies (0 = normal, 12 = severe dystrophic changes), quantitative myometry of biopsied muscles, global manual muscle testing scores, and frequency of wheelchair use.
  
  
  RESULTS
  Twenty-eight (37.8%) participants had 7-10 D4Z4 repeats, and compared to participants with 1-6 repeats, were diagnosed 6.6 years older (p = 0.17); had lower CpG methylation than would be predicted by D4Z4 repeat size (p = 0.04); had age-adjusted clinical severity 39.8 points lower (p = 0.004); had muscle pathology grades that were 2.4 points less severe (p < 0.0001); had quantitative myometry 28.3% predicted of normal higher (p = 0.002); had global manual muscle testing scores 0.6 higher (p = 0.005); and did not require wheelchairs.
  
  
  CONCLUSIONS
  Patients with FSHD with 7-10 D4Z4 repeats have milder disease than other genetically defined patients with FSHD1. The lower than predicted methylation in the 7-10 residual repeat group may suggest that additional epigenetic factors play a role in the severity of disease expression.
authors.affiliation: From the Department of Neurology (J.M.S.), University of Kansas Medical Center, Kansas City; the Department of Neurology (C.M.D., R.T.), University of Rochester Medical Center, NY; the Division of Human Biology (S.J.T.), Fred Hutchinson Cancer Research Center, Seattle, WA; and the Department of Human Genetics (R.J.L.F.L., S.M.v.d.M.), Leiden University Medical Center, the Netherlands. jstatland@kumc.edu.
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Statland
authors.affiliation: From the Department of Neurology (J.M.S.), University of Kansas Medical Center, Kansas City; the Department of Neurology (C.M.D., R.T.), University of Rochester Medical Center, NY; the Division of Human Biology (S.J.T.), Fred Hutchinson Cancer Research Center, Seattle, WA; and the Department of Human Genetics (R.J.L.F.L., S.M.v.d.M.), Leiden University Medical Center, the Netherlands.
authors.forename: Colleen M
authors.initials: CM
authors.lastname: Donlin-Smith
authors.affiliation: From the Department of Neurology (J.M.S.), University of Kansas Medical Center, Kansas City; the Department of Neurology (C.M.D., R.T.), University of Rochester Medical Center, NY; the Division of Human Biology (S.J.T.), Fred Hutchinson Cancer Research Center, Seattle, WA; and the Department of Human Genetics (R.J.L.F.L., S.M.v.d.M.), Leiden University Medical Center, the Netherlands.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Tapscott
authors.affiliation: From the Department of Neurology (J.M.S.), University of Kansas Medical Center, Kansas City; the Department of Neurology (C.M.D., R.T.), University of Rochester Medical Center, NY; the Division of Human Biology (S.J.T.), Fred Hutchinson Cancer Research Center, Seattle, WA; and the Department of Human Genetics (R.J.L.F.L., S.M.v.d.M.), Leiden University Medical Center, the Netherlands.
authors.forename: Richard J L F
authors.initials: RJ
authors.lastname: Lemmers
authors.affiliation: From the Department of Neurology (J.M.S.), University of Kansas Medical Center, Kansas City; the Department of Neurology (C.M.D., R.T.), University of Rochester Medical Center, NY; the Division of Human Biology (S.J.T.), Fred Hutchinson Cancer Research Center, Seattle, WA; and the Department of Human Genetics (R.J.L.F.L., S.M.v.d.M.), Leiden University Medical Center, the Netherlands.
authors.forename: Silvère M
authors.initials: SM
authors.lastname: van der Maarel
authors.affiliation: From the Department of Neurology (J.M.S.), University of Kansas Medical Center, Kansas City; the Department of Neurology (C.M.D., R.T.), University of Rochester Medical Center, NY; the Division of Human Biology (S.J.T.), Fred Hutchinson Cancer Research Center, Seattle, WA; and the Department of Human Genetics (R.J.L.F.L., S.M.v.d.M.), Leiden University Medical Center, the Netherlands.
authors.forename: Rabi
authors.initials: R
authors.lastname: Tawil
mesh_terms: D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020391:Muscular Dystrophy, Facioscapulohumeral / Q000175:diagnosis* / Q000235:genetics*; D010641:Phenotype; D011446:Prospective Studies; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics*; D055815:Young Adult