Abstract Details

Genetic Prevalence of Myotonic Dystrophy Type 1
Neuromuscular and Clinical Neurophysiology (EMG)
S23 - Genetic Muscle Disorders (3:52 PM-4:03 PM)
003
Prior studies have relied on individuals with a clinical diagnosis for determination of the prevalence.  This has resulted in prevalence estimates between 5.3 to 15.7 individuals per 100,000.  Since individuals with myotonic dystrophy type 1 may not have symptoms prior to the age of 50, it is possible that these prevalence estimates are lower than the true prevalence.  
To determine the genetic prevalence at birth of myotonic dystrophy type 1.
The study utilized de-identified, consecutive, newborn blood spots from New York State as the study population. DNA was extracted from blood spots and a triplet-primed PCR was performed to amplify the (CTG)n repeat in the 3’ untranslated region of the DMPK gene.  Post-amplification melt curve analysis was performed on the PCR products and four blinded reviewers scored samples for higher melting temperature profiles.  For those samples identified with melt curve profiles above the normal range, CTG repeat sizes were validated with fluorescently-labeled PCR and capillary electrophoresis (CE) sizing and with the Asuragen Amplidex PCR/CE DMPKkit.  
Using melt curve analysis we were able to discern between normal length repeats, premutations (35-49 repeats), and positive samples (>50 repeats).  From screening 32,923 newborn blood spots, we identified 13 samples with CTG repeat sizes from 50 to >200.  We also identified 17 samples with CTG repeat sizes from 39 to 49 (premutations). The genetic prevalence of DM1 (CTG repeat expansion>50) was 1:2532 (PRR 3.18, 95% CI 1.35-7.5), or 39.5 per 100,000 individuals.
The prevalence of myotonic dystrophy type 1 is significantly higher than previously reported.  
Authors/Disclosures
Nicholas E. Johnson, MD, FAAN (Virginia Commonwealth University)
PRESENTER 		Dr. Johnson has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Sarepta Therapuetics. Dr. Johnson has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Dyne Therapeutics. Dr. Johnson has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Vertex Pharma. Dr. Johnson has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Avidity. Dr. Johnson has received personal compensation in the range of $100,000-$499,999 for serving as a Consultant for Arthex. Dr. Johnson has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Juvena. Dr. Johnson has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Rgenta. Dr. Johnson has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Angle Therapeutics. Dr. Johnson has received personal compensation in the range of $500-$4,999 for serving as a Consultant for AskBio. Dr. Johnson has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Biogen. Dr. Johnson has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Argenx. Dr. Johnson has stock in Angle Therapeutics. Dr. Johnson has stock in Juvena Therapeutics. Dr. Johnson has stock in Myogene Therapies. The institution of Dr. Johnson has received research support from Novartis. The institution of Dr. Johnson has received research support from Takeda . The institution of Dr. Johnson has received research support from AMO Pharma. The institution of Dr. Johnson has received research support from Sarepta. The institution of Dr. Johnson has received research support from Dyne Therapeutics. The institution of Dr. Johnson has received research support from AskBio. The institution of Dr. Johnson has received research support from Pepgen. The institution of Dr. Johnson has received research support from ML Bio. The institution of Dr. Johnson has received research support from Vertex. The institution of Dr. Johnson has received research support from Arthex. The institution of Dr. Johnson has received research support from Avidity Biosciences. The institution of Dr. Johnson has received research support from Edgewise. Dr. Johnson has received intellectual property interests from a discovery or technology relating to health care.
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Russell Butterfield, MD, PhD, BS (University of Utah) Dr. Butterfield has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Sarepta. Dr. Butterfield has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Scholar Rock. Dr. Butterfield has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Reata. The institution of Dr. Butterfield has received research support from NIH. The institution of Dr. Butterfield has received research support from Ionis. The institution of Dr. Butterfield has received research support from CDC.
No disclosure on file
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