While the pro-fibrotic polymorphism in LTBP4 found in the DBA2/J background has not been implicated in Pompe disease, polymorphisms in angiotensin-converting enzyme (ACE) and alpha-actinin 3 (ACTN3) (De Filippi et al., 2014) impact disease onset within LOPD. Here, ACTN3 is linked to glycogen storage disease II.