Myotonic Dystrophy 2

Clinical Characteristics
Ocular Features: 

Polychromatic lens opacities and posterior subcapsular sclerosis are found in 15-30% of patients. 

Ptosis, ophthalmoplegia and strabismus are not features of DM2.As many as 25% of patients with DM have a pigmentary retinopathy, usually in a butterfly pattern.

Systemic Features: 

Symptoms of myotonia usually appear in the third and fourth decades of life while evidence of limb girdle muscle weakness usually appears much later.  There is no infancy or childhood form of the disease and developmental delays do not occur.   In some patients the proximal muscles seem to be more affected than distal muscles and such cases are sometimes referred to as PROMM disease.  In these patients the neck and finger flexors may be the first to be affected.  However, there is considerable clinical variability.  Facial weakness is minimal.  Eventually both proximal and distal muscles weaken.  Myalgia of a burning, tearing nature can be debilitating.  Cardiac arrhythmias occur in a minority of patients.  Frontal balding is characteristic.  The long-term prognosis is better than in patients with myotonic dystrophy 1 (160900), and some but not all reports suggest fewer individuals experience age-related cognitive decline.  Insulin insensitivity and testicular failure occur in approximately half of patients.

PROMM disease and DM2 are now generally accepted as the same disease and the latter designation is preferred.


Like classic myotonic dystrophy 1 (160900), this disorder also results from an abnormal number of repeats (in this case of CCTG).  Up to 30 tetranucleotide repeats in CNBP (3q21.3) is normal but patients with myotonic dystrophy 2 may have 11,000 or more and the number increases with age.  The repeat length may diminish with generational transmission.  Unlike DM 1, the repeat number does not seem to correlate with disease severity.  Both DM1 and DM2 are inherited in an autosomal dominant pattern.

Treatment Options: 

There is no treatment for the muscle disease but many patients require analgesic medication for muscle pain.  Visually significant cataracts should be removed.  Some patients require supportive care.

Article Title: 


Makino S, Ohkubo Y, Tampo H. Butterfly-shaped Pattern Dystrophy in Myotonic Dystrophy. Intern Med. 2012;51(16):2253-4. Epub 2012 Aug 15.

PubMedID: 22892517

Tieleman AA, Jenks KM, Kalkman JS, Borm G, van Engelen BG. High disease impact of myotonic dystrophy type 2 on physical and mental functioning. J Neurol. 2011 Oct;258(10):1820-6.

PubMedID: 21461958

Ranum LP, Rasmussen PF, Benzow KA, Koob MD, Day JW. Genetic mapping of a second myotonic dystrophy locus. Nat Genet. 1998 Jun;19(2):196-8.

PubMedID: 9620781

Ricker K, Koch MC, Lehmann-Horn F, Pongratz D, Speich N, Reiners K, Schneider C, Moxley RT 3rd. Proximal myotonic myopathy. Clinical features of a multisystem disorder similar to myotonic dystrophy. Arch Neurol. 1995 Jan;52(1):25-31.

PubMedID: 7826272

Kimizuka Y, Kiyosawa M, Tamai M, Takase S. Retinal changes in myotonic dystrophy. Clinical and follow-up evaluation. Retina. 1993;13(2):129-35.

PubMedID: 8337494

Ashizawa T, Hejtmancik JF, Liu J, Perryman MB, Epstein HF, Koch DD. Diagnostic value of ophthalmologic findings in myotonic dystrophy: comparison with risks calculated by haplotype analysis of closely linked restriction fragment length polymorphisms. Am J Med Genet. 1992 Jan 1;42(1):55-60.

PubMedID: 1364051