PROJECT SUMMARY/ABSTRACT Spinal muscular atrophy (SMA) is one of the most common inherited cause of death in infants and young children. SMA is caused by the deletion or mutation in the survival of motor neuron 1 (SMN1) gene, leading to a deficiency of the ubiquitously expressed SMN protein. Recent approved therapies increase SMN protein and partially correct the motor neuron loss and muscle degeneration that are hallmarks of the disease. However, SMA patients require critical care as a result of cardiopulmonary impairment and opportunistic infections. This observation, together with extensive new preliminary data, leads us to hypothesize that SMN-deficiency impairs cardiomyocyte function, representing a previously unrecognized contribution of the cardiovascular system on SMA disease pathology. To test this hypothesis, we will use primary cardiomyocytes from a mouse model of the disease and human cardiomyocytes derived from SMA patient induced pluripotent stem cells (iPSC) to determine the consequences of SMN deficiency on contractile function (Aim 1), the molecular mechanisms leading to impaired contraction (Aim 2), and characterize cardiovascular deficiencies following SMN restoration in SMA mice (Aim 3). The preliminary results using our unique approach are already providing novel mechanistic insight into a poorly understood aspect of the SMA disease process which could be critically important when designing strategies to manage the disease clinically.