myotonic dystrophy type 1
MIM.160900 19q13.2-q13.3
Myotonic dystrophy type 1 is an autosomal dominant disorder characterized by myotonia, muscular dystrophy, cataracts, hypogonadism, frontal balding, and ECG changes.
Etiology
Myotonic dystrophy type 1 (Steinert disease) is caused by CTG triplet expansion in the dystrophia myotonica protein kinase gene (DMPK) (MIM.605377) at 19q13.2-q13.3.
- Normal - 5 to 27 copies of repeat
- Affected, Mild - 50-80 repeats
- Adult Onset - 100-500 repeats
- Congenital - 500-2,000 repeats
- possible negative repeat expansion (reverse anticipation)
Synopsis
cataract
swallowing and speech disability
poor feeding (congenital form)
atrial arrhythmias
cardiac conduction block
cholelithiasis
recurrent intestinal pseudoobstruction
hypogonadism
testicular atrophy
uncoordinated uterine contraction
frontal balding (male pattern baldness)
muscular anomalies
- myotonia
- weakness
- wasting, especially temporal, neck, and facial
- respiratory distress (congenital form)
- bilateral facial weakness (congenital form)
- absence of myotonia in infancy (congenital form)
multiple pilomatricomas
cerebrospinal anomalies
- mild cognitive deterioration in adults
- swallowing and speech disability
- hypotonia (congenital form)
- severe mental retardation (congenital form)
congenital forms
- reduced fetal movements (congenital form)
- polyhydramnios
Videos
muscular dystrophy by Washington Deceit