How does CTG repeat length correlate with DM1 phenotype?

50–150 repeats: mild (cataracts, mild myotonia). 100–1000: classic DM1 (weakness, myotonia, cardiac conduction defects). >1000: severe or congenital DM1. Somatic mosaicism means blood repeat length may underestimate muscle involvement.

What cardiac monitoring is required in DM1?

Annual 12-lead ECG and periodic Holter monitoring are recommended due to progressive cardiac conduction disease. PR prolongation >240ms, QRS >120ms, or symptoms prompt electrophysiology study and consideration of pacemaker or ICD implantation.

Myotonic Dystrophy CTG Repeat Score

Correlate CTG repeat length with phenotype severity in Myotonic Dystrophy Type 1, from asymptomatic to congenital DM1 presentation.

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Frequently Asked Questions

How does CTG repeat length correlate with DM1 phenotype?

What cardiac monitoring is required in DM1?