SMN1 variants identified by false-positive SMA newborn screening tests: Therapeutic hurdles and functional and epidemiological solutions

Two different 4-base-pair deletions in SMN1 that cause a similar frameshift led to false-positive SMA newborn screening results. Integrating genomic, functional, and population data clarified diagnosis, preventing unnecessary treatment, and demonstrated that a previously undescribed SMN protein can preserve motor function despite the absence of wild-type full-length SMN.