Myotonic dystrophy phenotype without expansion of (CTG)n repeat: An entity distinct from proximal myotonic myopathy (PROMM)?

Claudia Abbruzzese, Ralf Krahe, Michele Liguori, Daniela Tessarolo, Michael J. Siciliano, Tetsuo Ashizawa, Manlio Giacanelli

Research output: Contribution to journalArticle

27 Scopus citations

Abstract

Myotonic dystrophy (DM) is associated with an expansion of an unstable (CTG)n repeat in the 3' untranslated region of the DM protein kinase (DMPK) gene on chromesome 19q13.3. We studied six patients from two families who showed no expansions of the repeat, in spite of their clinical diagnosis of DM. These patients had multi-systemic manifestations that were distinguishable from those seen in other myotonic disorders, including proximal myotonic myopathy (PROMM). In one additional family, two symptomatic members showed no expanded (CTG)n repeats, while their affected relatives had the expanded repeats. DM haplotype analysis failed to exclude the DMPK locus as a possible site of mutation in each family; however, DMPK mRNA levels were normal. We conclude that a mutation(s) other than the expanded (CTG)n repeat can cause the DM phenotype.The mutation(s) in these families remain(s) to be mapped and characterized.

Original languageEnglish (US)
Pages (from-to)715-721
Number of pages7
JournalJournal of Neurology
Volume243
Issue number10
DOIs
StatePublished - 1996

Keywords

  • CTG repeat
  • Myotonic dystrophy
  • Phenocopy
  • Proximal myotonic myopathy

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology

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