GTR Home > Conditions/Phenotypes > Steinert myotonic dystrophy syndrome

Disease characteristics

Excerpted from the GeneReview: Myotonic Dystrophy Type 1
Myotonic dystrophy type 1 (DM1) is a multisystem disorder that affects skeletal and smooth muscle as well as the eye, heart, endocrine system, and central nervous system. The clinical findings, which span a continuum from mild to severe, have been categorized into three somewhat overlapping phenotypes: mild, classic, and congenital. Mild DM1 is characterized by cataract and mild myotonia (sustained muscle contraction); life span is normal. Classic DM1 is characterized by muscle weakness and wasting, myotonia, cataract, and often cardiac conduction abnormalities; adults may become physically disabled and may have a shortened life span. Congenital DM1 is characterized by hypotonia and severe generalized weakness at birth, often with respiratory insufficiency and early death; intellectual disability is common.

Associated genes

Clinical features

  • Myotonia
  • Intellectual disability, severe
  • Strabismus
  • Hypertonia
  • Decreased fetal movement
  • Irregular heart beat
  • Mask-like facies
  • EMG abnormality
  • Respiratory insufficiency
  • Obsessive-compulsive trait
  • Facial diplegia
  • Intellectual disability, progressive
  • Dysphagia
  • Cognitive impairment
  • Amyotrophy
  • Frontal balding
  • Cataract
  • Atrial fibrillation
  • Atrial flutter
  • Hydrocephalus
  • First degree atrioventricular block
  • Feeding difficulties in infancy
  • Cryptorchidism
  • Testicular atrophy
  • Hypogonadism
  • Abnormality of the endocrine system
  • Cholelithiasis
  • Muscular hypotonia
  • Polyhydramnios
  • Cerebral atrophy
  • Respiratory distress
  • Excessive daytime sleepiness
  • Malformation of the heart and great vessels
  • Abnormality of the hip bone
  • Hernia of the abdominal wall
  • Facial palsy
  • Abnormality of the upper urinary tract
  • Non-midline cleft lip
  • Abnormal hair quantity
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