LB: Pediatric FSHD in the US: Results from the US National Registry for FSHD


Clinical Management

Poster Number: T435


Natalie Katz, MD, PhD, Duke University Medical Center, Lucas McHan, University of Rochester, Rabi Tawil, MD, University of Rochester, Michael McDermott, PhD, University of Rochester, Jeffrey Statland, MD, University of Kansas

Background: Pediatric-onset FSHD accounts for approximately 20% of individuals with facioscapulohumeral muscular dystrophy (FSHD). Half of these individuals meet criteria for early-onset FSHD, which is defined as onset of facial weakness prior to age five, and shoulder girdle weakness prior to age 10. Few prospective studies exist to inform our understanding of disease progression in pediatric FSHD, and creates a barrier to drug development and clinical care for children with FSHD.

Objective/Methods: We analyzed prospectively collected data from participants in the US National Registry for FSHD (The Registry) who were diagnosed ≤ 18 years of age to understand disease progression in this population. Early-onset was defined as diagnosis ≤ 10 years of age.

Results: A total of 166 individuals with genetically confirmed FSHD type 1 or type 2 were identified, with an average of 10.4 years (median 9 years, range 0-21) of follow up surveys. Consistent with the literature, individuals with 1-3 D4Z4 repeats were diagnosed at a younger age than individuals with 4+ D4Z4 repeats (p < 0.001), and progressed to wheelchair use at a younger age (p < 0.001). When separated by sex, we found that females were diagnosed at a significantly younger age than males (p < 0.001), independent of D4Z4 repeat size (p < 0.001), and were more likely to report diagnosis ≤ 10 years of age (p < 0.001). Females were also more likely to report facial weakness as their initial symptom (p = 0.001). Females with early-onset FSHD progressed to wheelchair use at a younger age than males (p < 0.001)

Conclusions: To date, this is the largest analysis of prospectively collected data from individuals with FSHD in the US who were diagnosed during their pediatric years. These findings support the notion that pediatric-onset FSHD is part of the clinical spectrum of FSHD. Surprisingly, these data suggest that females are more severely affected by pediatric-onset FSHD than males. Larger, prospective studies are needed to further understand disease progression in pediatric FSHD and if there are sex differences in disease severity, which could have implications for clinical care and trial stratification.