IllnessDystrophy, myotonic 1

X

Myotonic dystrophy (Dystrophia myotonica, DM) is a multisystemic disease affecting the skeletal and smooth muscles, brain, eyes, heart, lungs, gastrointestinal and endocrine systems. DM1 is divided into mild (late onset), classic (adult onset), infantile/adolescent and congenital forms. DM1 is a progressive disease and leads to gradual deterioration in many areas such as muscle strength and cognition. Children with infantile onset (<10 years of age, after early childhood) often have similar symptoms and a similar course of disease as children with congenital onset. Infants with congenital onset may be born with hypotension, breathing or feeding problems and difficulty in swallowing. Global developmental delay is often observed in the early years. Distal muscular atrophy, weakness and the characteristic myotonia may not be detected until school age or even later. In the rarer DM2, no congenital or early childhood forms are known. The two forms DM1 and DM2 are transmitted autosomal dominantly and are caused by various repetitive expansion mutations. In DM1 the continuum ranges from mild to severe disease in approximate correlation with the lengths of the trinucleotide repeat (CTG) blocks in the DMPK gene; trinucleotide blocks exceeding 50 CTGs are fully penetrant. In DM2, the expanded CNBP alleles may include 75-11 000 (CTG) repeats; penetrance is age dependent and up to 100%. The absence of repeat expansions in the DMPK and CNBP genes virtually rules out DM.

Reference: https://www.ncbi.nlm.nih.gov/books/NBK1165/

• Alias: Curschmann-Steinert
• Alias: Dystrophia myotonica 1 (DMPK)
• Alias: Dystrophia myotonica 2 (CNBP)
• DM1: Steinert myotonic dystrophy, Steinert disease
• DM2: Proximal myotonic dystrophy, Ricker disease
• Myotonic dystrophy type 1, DM1 (DMPK)
• Myotonic dystrophy type 2, DM2 (CNBP)