title: Genotype-phenotype study in an FSHD family with a proximal deletion encompassing p13E-11 and D4Z4.
abstract: BACKGROUND
  In the majority of facioscapulohumeral muscular dystrophy (FSHD) cases, the molecular basis of the disease is due to loss of subtelomeric D4Z4 repeat units at 4q35. Occasionally, an apparent absence of the contracted D4Z4 repeat is associated with FSHD. One explanation for this finding is a deletion in the region proximal to the D4Z4 repeat array that encompasses the p13E-11 (D4F104S1) probe-binding site used in the DNA diagnosis. The frequency of such proximally extended deletions is unknown, and to date, few patients have been described due to the difficulties in the molecular identification of such cases.
  
  
  METHODS
  We describe a family (DUK 2531) in which a contracted D4Z4 allele and a large proximal deletion of approximately 75 kb are segregating to 11 individuals. This is the largest deletion identified to date. Family DUK 2531 was initially thought to have normal D4Z4 fragment size and therefore unlinked to the 4q35 region (FSHD1B).
  
  
  RESULTS
  Further molecular analysis of DUK 2531 reveals the presence of 10 repeat units (33 kb). The extended deletion includes the probe p13E-11 and B31 binding sites, the inverted repeat D4S2463, and genes FRG2 and TUBB4Q.
  
  
  CONCLUSIONS
  Despite the length of the proximal deletion in this family, the range and severity of the clinical manifestations are typical for the disorder. Because such deletions can lead to misinterpretation in the diagnostic setting, this suggests the need for additional diagnostic tests in facioscapulohumeral muscular dystrophy.
authors.affiliation: Center for Human Genetics, Duke University Medical Center, Durham, NC 27710, USA.
authors.forename: K L
authors.initials: KL
authors.lastname: Deak
authors.forename: R J L F
authors.initials: RJ
authors.lastname: Lemmers
authors.forename: J M
authors.initials: JM
authors.lastname: Stajich
authors.forename: R
authors.initials: R
authors.lastname: Klooster
authors.forename: R
authors.initials: R
authors.lastname: Tawil
authors.forename: R R
authors.initials: RR
authors.lastname: Frants
authors.forename: M C
authors.initials: MC
authors.lastname: Speer
authors.forename: S M
authors.initials: SM
authors.lastname: van der Maarel
authors.forename: J R
authors.initials: JR
authors.lastname: Gilbert
mesh_terms: D000328:Adult; D002869:Chromosome Aberrations; D002894:Chromosomes, Human, Pair 4 / Q000235:genetics*; D004252:DNA Mutational Analysis; D005260:Female; D017353:Gene Deletion; D018628:Gene Dosage / Q000235:genetics; D005787:Gene Frequency / Q000235:genetics; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D005820:Genetic Testing; D005838:Genotype; D006801:Humans; D008297:Male; D018908:Muscle Weakness / Q000175:diagnosis / Q000235:genetics / Q000503:physiopathology; D018482:Muscle, Skeletal / Q000473:pathology / Q000503:physiopathology; D020391:Muscular Dystrophy, Facioscapulohumeral / Q000175:diagnosis / Q000235:genetics* / Q000503:physiopathology*; D009154:Mutation / Q000235:genetics*; D010375:Pedigree; D010641:Phenotype