MYOTONIC DYSTROPHY TYPE I (DM1)

Diagnostic Testing
with Genomic Unity®

Genetic Testing for Myotonic Dystrophy Type I (DM1)

CTG repeat expansion testing of the DMPK gene

Myotonic Dystrophy Type I, also known as Steinert’s disease, is a condition that affects skeletal and smooth muscles. It may also affect the eyes, the heart, the endocrine system and the central nervous system.

 

Clinical features of Myotonic Dystrophy Type I

Clinical symptoms may range from mild to severe, with cases breaking down into three general categories:

  • Mild: characterized by adult onset of mild symptoms of myotonia and sometimes cataracts, patients with the mild form of DM1 typically experience a normal lifespan
  • Classic: characterized by adult onset of muscle weakness, atrophy, myotonia, cataracts and cardiac issues, patients with the classic form of DM1 may experience a shortened lifespan
  • Congenital: characterized by presence of hypotonia and generalized weakness at birth, the congenital form of DM1 often leads to early death. Respiratory insufficiency and intellectual disability are common clinical features

 

Diagnosis of Myotonic Dystrophy Type I

Myotonic Dystrophy Type I is caused by expansion of the CTG repeat within the 3′ untranslated region of the DMPK gene.

Genomic Unity® Neuromuscular Disorders Analysis is a genetic test that uses a PCR-free whole genome sequencing (WGS) methodology. The single method platform enables comprehensive analysis of all major variant types within genes associated with neuromuscular disorders. This test specifically includes sequence, del/dup and CTG repeat expansion analysis of the DMPK gene.

 

Differential diagnosis of myotonic disorders

With its broad coverage of >120 genes associated with neuromuscular disorders, Genomic Unity® Neuromuscular Disorders Analysis makes it possible to differentiate Myotonic Dystrophy Type I from among heterogeneous myotonic disorders with overlapping clinical features.

Genomic Unity® Neuromuscular Disorders Analysis additionally includes:

  • sequence, del/dup and CCTG repeat expansion analysis of the CNBP gene which causes the oftentimes less severe Myotonic Dystrophy Type II (DM2)
  • sequence and del/dup analysis of CLCN1 and other genes that cause myotonia congenita
  • sequence and del/dup analysis of SCN4A and other genes that cause Paramyotonia Congenita, Potassium aggravated myotonia,  Potassium-sensitive periodic paralysis and other sodium channel myotonias

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