Muscle ultrasound in patients with late-onset Pompe disease identified by newborn screening.

Importance: Implementation of newborn screening (NBS) in the United States now detects infants with late-onset Pompe disease (LOPD), a lysosomal storage disease characterized by slowly progressive muscle weakness, and detailed clinical evaluation has identified early muscle weakness. Biomarkers may be uninformative; thus, non-invasive imaging is needed to assess early LOPD muscle changes. Muscle ultrasound (US) measuring echointensity (EI) is a non-invasive measure of muscle health.

Early clinical phenotype of late onset Pompe disease: Lessons learned from newborn screening.

Purpose: Thoroughly phenotype children with late-onset Pompe disease (LOPD) diagnosed via newborn screening (NBS) to provide guidance for long-term follow up.

Methods: Twenty infants ages 6-21 months with LOPD diagnosed by NBS underwent systematic clinical evaluation at Duke University including cardiac imaging, biomarker testing, physical therapy evaluation, and speech-language pathology evaluation.

Results: Of the 20 infants, four were homozygous for the "late-onset" IVS1 splice site variant c.