Prevalence of congenital, distal, Emery-Dreifuss, and limb-girdle muscular dystrophies, Muscular Dystrophy Surveillance Tracking and Research Network

Topic:

Other

Poster Number: P104

Author(s):

Kristin Conway, PhD, University of Iowa, Katherine Mathews, MD, University of Iowa, Jonathan Suhl, PhD, University of Iowa, Paul A Romitti, PhD, University of Iowa, Peter B Kang, MD, University of Minnesota, Manju Jayaram, MPH, New York State Department of Health, Emma Ciafaloni, MD, University of Rochester, Nedra Whitehead, PhD, Research Triangle International, Reba Berry, RN, South Carolina Department of Public Health, Swamy Venkatesh, MD, University of South Carolina, Russell Butterfield, MD, PhD, Univeristy of Utah, Madeline Rice, PhD, Milken Institute School of Public Health, Amy Harper, MD, VCU Health, Joyce T Alese, MD, MPH, Centers for Disease Control and Prevention, Catharine Riley, PhD, MPH, Centers for Disease Control and Prevention

Background: Knowing prevalence of genetically defined muscular dystrophies is important when considering trials for novel therapies and when considering resources required for clinical care. Congenital (CMD), Emery-Dreifuss (EDMD), distal (DD), and limb-girdle (LGMD) muscular dystrophies are individually rare. There is limited prevalence data in the United States (US) and available data varies in method of ascertainment.
Objective: To estimate period prevalence rates (PR) per 100,000 people using standardized clinical phenotypes from the US population-based Muscular Dystrophy Surveillance, Tracking, and Research Network (MD STARnet).
Methods: People with health encounters during 2008-2019 diagnosed with CMD, EDMD, DD, or LGMD in six areas (Florida [23 counties], Iowa, western New York [21 counties], North Carolina [33 counties], South Carolina, and Utah) were identified. Clinical phenotypes (MD type/subtype) and case classifications (definite/probable/possible/asymptomatic) were assigned using standard case definitions for each MD type. PRs were estimated for each phenotype, excluding people with possible MD. The denominator was the average mid-year Census population estimates for the years 2008-2019.
Results: The PR for CMD (n=125) was 0.53 per 100,000 people (95% confidence interval [CI]:0.44-0.63); 66.4% were genetically confirmed. The most prevalent subtype was collagen VI. The PR for DD (n=40) was 0.17 (95%CI:0.12-0.23); 50% were genetically confirmed. GNE was the most prevalent variant identified. The PR for EDMD (n=56) was 0.24 (95%CI:0.18-0.31); 75% were genetically confirmed. EDMD2 was the most prevalent subtype. LGMD was the most common MD (n=440) with a PR of 1.85 (95%CI:1.68, 2.03); 50.2% were genetically confirmed. The most prevalent autosomal dominant LGMD subtype was LGMD1B. The three most common autosomal recessive LGMD subtypes were LGMDR1/2A, LGMDR2/2B, and LGMDR9/2I.
Conclusion: We report prevalence rates for CMD, DD, EDMD and LGMD within six US geographical areas using standard clinical phenotypes. Our findings can inform clinical trial readiness in the US for these MD types.