Small muscle protein, X-linked (SMPX) plays a role in skeletal muscle hypertrophy34, and Protein phosphatase 3 catalytic subunit alpha (PPP3CA) plays a critical role in controlling skeletal muscle fiber type35, while abnormal splicing of the penultimate exon of dystrophin (DMD) compromises muscle fiber maintenance in myotonic dystrophy36. The gene discussed is PPP3CA; the disease is Duchenne muscular dystrophy.