A new opinion article in JAMA Neurology argues that now may be an opportune time to begin newborn screening for Duchenne muscular dystrophy (DMD). With US Food and Drug Association (FDA) approval of 4 molecular therapies for DMD — eteplirsen, golodirsen, vitolarsen, and casimersen — along with a commercially available immunoassay specific to the skeletal muscle isoform of creatine kinase (CK-MM), the authors argue that steps should be taken to begin systematic implementation of newborn screening.
Chrzanowski et al stated: “Newborn screening for DMD will identify affected infants early in the disease course, allowing for more systematic testing of earlier interventions, with the ultimate hope of better longitudinal clinical outcomes.”
DMD is the most common form of muscular dystrophy and the mean age of diagnosis is 4.4 years old. Despite this, treatments have currently only been studied in boys aged 6 to 15 years. The earlier age of diagnosis combined with laboratory and noninvasive techniques suggest that subclinical disease occurs earlier than this age group. The authors stated that further investigation is needed to determine if earlier intervention improves outcomes but this could be facilitated by newborn screening to identify potential study participants.
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There are possible unintended consequences of newborn screening, however, including false positives and negatives. False positives can be mitigated through standardized protocols for further genetic testing and when to inform families, according to the article’s authors. The assay may pick up other diseases which also feature elevated CK-MM levels such as other forms of muscular dystrophy that do not currently have treatment options. False negatives may also occur in patients with other forms of muscular dystrophy, such as limb-girdle and facioscapulohumeral, which may have only mildly elevated CK-MM levels.
Several potential barriers to newborn screening exist, including the regional variation in the availability of pediatric neuromuscular neurologists, geneticists, and genetic counselors that would be necessary for the optimal implementation of testing protocols. Funding and infrastructure will also need to be secured before the CK-MM-specific assay is added to the Recommended Universal Screening Panel for newborns.
Clear protocols and management plans to guide families and physicians will be necessary for the realization of the program but the article’s authors point to the successful model implemented in spinal muscular atrophy (SMA) as inspiration.
Chrzanowski SM, McAnally MM, Kang PB. An opportune time for newborn screening in Duchenne muscular dystrophy. JAMA Neurol. Published online June 21, 2021. doi:10.1001/jamaneurol.2021.1782