CST3 and spinal muscular atrophy: <h4>Background</h4>This study aimed to validate the utility of serum creatinine (Cr), creatinine-to-cystatin C ratio (CCR) and creatinine muscle index (CMI) as biomarkers in Chinese pediatric patients with spinal muscular atrophy (SMA).<h4>Methods</h4>A retrospective cohort of 21 pediatric patients with 5q-spinal muscular atrophy (5q-SMA) was followed over 18-month after initiating nusinersen therapy.