P610: Identification of Trinucleotide Repeat Expansions in DMPK Using Rapid Whole Genome Sequencing

Myotonic dystrophy type 1 (DM1) is an autosomal dominant multisystem disorder primarily characterized by delayed muscle relaxation, skeletal muscle weakness, early-onset cataracts, cardiomyopathy, diabetes, and gonadal failure. The disease is caused by trinucleotide (CTG) repeat expansion (TRE) exceeding 50 copies in the 3’ untranslated region (UTR) of the DMPK gene which encodes a serine-threonine protein kinase. Disease severity and age of onset correlate with the number of CTG repeats. Specifically, mild, late onset DM1 occurs with 50–∼150 repeats, whereas classic, young adult-onset DM1 occurs with ∼100- ∼1,000 repeats, and the most severe, congenital form occurs with >1,000 repeats.