Clinical Indication ID & Name
Myotonic dystrophy type 2 (DM2)
Test Group
Neurology
Specialties
Test code
R410.1
Test name
N/A
Target genes
CNBP (ZNF9) STR
Test scope
n/a
Test method/ technology
STR testing
Optimal Family Structure
n/a
Eligibility Criteria
1. Adult with muscle weakness, usually proximal, and one of the following:
a. Clinical Myotonia: of grip or on percussion
b. EMG evidence of myotonic discharges
c. Cataracts (fine dust like opacities on the outer layers of the lens that are highly coloured and iridescent, producing a “Christmas Tree” appearance)
d. Three or more supportive features (from list below)
e. Family History suggestive of autosomal dominant inheritance
2. AND DM1 excluded first if the clinical presentation/Family history could easily fit DM1
3. OR Family history of mutation positive DM2
Additional supportive features:
• Elevated serum CK
• Insulin-insensitive type 2 diabetes
• Testicular failure
• Cardiac conduction defects
• Low serum IgG or IgM
• Muscle biopsy showing atrophic fibres and proliferation of fibres with central nuclei
• Excessive daytime sleepiness
• Mildly elevated liver function tests (LFT)
• Muscle pain
Commissioning group
Specialised
Overlapping idications
• R72 Myotonic dystrophy type 1 should be used prior to this indication unless there is clinical suspicion of myotonic dystrophy type 2 • R381 Other rare neuromuscular disorders should be used where clinical features are atypical and a broader range of genes are potentially causative
Address for samples/request forms
North Thames GLH, Rare & Inherited Disease Genomic Laboratory
Specimen Reception, Level 5 Barclay House, 37 Queen Square,
London WC1N 3BH
Contact with queries
Supporting documents
n/a
Education resources
n/a
Service updates
n/a
Consent record
See consent guidance in test request form
Sample requirements
See sample guidance in test request form