International Journal of Molecular Sciences (Apr 2020)

Interpretation of the Epigenetic Signature of Facioscapulohumeral Muscular Dystrophy in Light of Genotype-Phenotype Studies

  • Ana Nikolic,
  • Takako I Jones,
  • Monica Govi,
  • Fabiano Mele,
  • Louise Maranda,
  • Francesco Sera,
  • Giulia Ricci,
  • Lucia Ruggiero,
  • Liliana Vercelli,
  • Simona Portaro,
  • Luisa Villa,
  • Chiara Fiorillo,
  • Lorenzo Maggi,
  • Lucio Santoro,
  • Giovanni Antonini,
  • Massimiliano Filosto,
  • Maurizio Moggio,
  • Corrado Angelini,
  • Elena Pegoraro,
  • Angela Berardinelli,
  • Maria Antonetta Maioli,
  • Grazia D’Angelo,
  • Antonino Di Muzio,
  • Gabriele Siciliano,
  • Giuliano Tomelleri,
  • Maurizio D’Esposito,
  • Floriana Della Ragione,
  • Arianna Brancaccio,
  • Rachele Piras,
  • Carmelo Rodolico,
  • Tiziana Mongini,
  • Frederique Magdinier,
  • Valentina Salsi,
  • Peter L. Jones,
  • Rossella Tupler

DOI
https://doi.org/10.3390/ijms21072635
Journal volume & issue
Vol. 21, no. 7
p. 2635

Abstract

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Facioscapulohumeral muscular dystrophy (FSHD) is characterized by incomplete penetrance and intra-familial clinical variability. The disease has been associated with the genetic and epigenetic features of the D4Z4 repetitive elements at 4q35. Recently, D4Z4 hypomethylation has been proposed as a reliable marker in the FSHD diagnosis. We exploited the Italian Registry for FSHD, in which FSHD families are classified using the Clinical Comprehensive Evaluation Form (CCEF). A total of 122 index cases showing a classical FSHD phenotype (CCEF, category A) and 110 relatives were selected to test with the receiver operating characteristic (ROC) curve, the diagnostic and predictive value of D4Z4 methylation. Moreover, we performed DNA methylation analysis in selected large families with reduced penetrance characterized by the co-presence of subjects carriers of one D4Z4 reduced allele with no signs of disease or presenting the classic FSHD clinical phenotype. We observed a wide variability in the D4Z4 methylation levels among index cases revealing no association with clinical manifestation or disease severity. By extending the analysis to family members, we revealed the low predictive value of D4Z4 methylation in detecting the affected condition. In view of the variability in D4Z4 methylation profiles observed in our large cohort, we conclude that D4Z4 methylation does not mirror the clinical expression of FSHD. We recommend that measurement of this epigenetic mark must be interpreted with caution in clinical practice.

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