Evidence Regarding Duchenne Muscular Dystrophy Newborn Screening

Abstract

Variants in the DMD gene, located on the X chromosome, cause Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD). DMD reportedly affects about 2 per 10,000 newborn males, leading to progressive weakness and premature death, typically from respiratory or cardiac complications. The average age of diagnosis in the United States (US) over the past four decades has been 4.5 to 5 years. The availability of targeted therapies and the long diagnostic odyssey have led to advocacy for newborn screening (NBS). Studies of caregivers of children with DMD describe support for NBS. Meeting abstracts, which may have bias, suggest earlier identification in a child following DMD diagnosis in an older brother improves outcomes. Ohio and Minnesota include DMD NBS, and other states are planning implementation. DMD NBS is based on measuring the muscle isoform of creatine kinase (CK-MM), which is elevated due to muscle damage. Infants with borderline CK-MM levels can be retested after at least one week to determine if elevations are birth related. Molecular analysis in infants with significantly elevated CK-MM can identify DMD variants associated with DMD or BMD. Screening accuracy depends on the testing algorithm. Although treatment with glucocorticoids or related medications can improve outcomes for DMD despite side effects, the optimal age of initiation is unclear. Efficacy of the Food and Drug Administration-approved gene therapy has not been established, and it has a rare risk of hepatotoxicity. Genotype-specific exon-skipping medications, indicated for 27% of cases, may improve outcomes, but clinical benefit is not definitively established.