Proximal myotonic myopathy: Clinical, neuropathologic, and molecular genetic features

S. Eisenschenk, W. J. Triggs, G. S. Pearl, A. M. Rojiani

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


The primary genetic abnormality in myotonic dystrophy (DM) is an expansion of the CTG trinucleotide repeat on chromosome 19q. Recently, patients with similar clinical features, but without this genetic alteration, have been designated as proximal myotonic myopathy (PROMM). We describe two additional cases of PROMM, both of whom presented with clinical features suggestive of myotonic dystrophy. The patients had electromyographic (EMG) evidence of myotonia, normal cardiac evaluation, and no cataracts. Genetic analysis of peripheral blood leukocytes revealed no expansion of the trinucleotide repeat by polymerase chain reaction (PCR) and Southern blot analysis. Muscle biopsies in both cases were significant with features suggestive of myotonic dystrophy, such as large numbers of fibers containing multiple internal nuclei, occasional nuclear chains, and fiber atrophy, although sarcoplasmic masses and ring fibers were absent. These cases illustrate the clinical and neuropathologic findings of PROMM and underline the importance of correlating these aspects with genetic studies in patients with myotonic muscle disorders.

Original languageEnglish (US)
Pages (from-to)140-146
Number of pages7
JournalAnnals of Clinical and Laboratory Science
Issue number2
StatePublished - Apr 28 2001
Externally publishedYes


  • Myotonic dystrophy (DM)
  • Polymerase chain reaction
  • Proximal myotonic myopathy (PROMM)
  • Southern blot
  • Trinucleotide repeats

ASJC Scopus subject areas

  • Microbiology
  • Immunology and Allergy
  • Pathology and Forensic Medicine
  • Immunology
  • Molecular Biology
  • Hematology
  • Clinical Biochemistry
  • Medical Laboratory Technology


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