ObjectiveTo determine changes in serum profiles and kidney tissues from patients with spinal muscular atrophy (SMA) type 1 compared with age- and sex-matched controls.MethodsIn this cohort study, we investigated renal structure and function in infants and children with SMA type 1 in comparison with age- and sex-matched controls.ResultsPatients with SMA had alterations in serum creatinine, cystatin C, sodium, glucose, and calcium concentrations, granular casts and crystals in urine, and nephrocalcinosis and fibrosis. Nephrotoxicity and polycystic kidney disease PCR arrays revealed multiple differentially expressed genes, and immunoblot analysis showed decreased calcium-sensing receptors and calbindin and increased insulin-like growth factor–binding proteins in kidneys from patients with SMA.ConclusionsThese findings demonstrate that patients with SMA type 1, in the absence of disease-modifying therapies, frequently manifest impaired renal function as a primary or secondary consequence of their disease. This study provides new insights into systemic contributions to SMA disease pathogenesis and the need to identify coadjuvant therapies.