A 2-month-old male with dysmorphic facies, neonatal thrombocytopenia, left congenital cataract, and long bone abnormalities became hypotensive with ST depression on induction of anesthesia for congenital cataract repair. Echocardiogram demonstrated decreased left ventricular function (ejection fraction 46%), mild mitral valve regurgitation (MR), and regional wall motion abnormalities. The left coronary artery could not be visualized. Subsequent cardiac catheterization confirmed atresia of the left main coronary artery. The patient underwent cardiac surgery with coronary artery bypass grafting of the left internal mammary artery to the left anterior descending coronary artery. His postoperative course was uncomplicated, his ventricular function normalized, and he was discharged home. Over the next few months, he developed progressive, severe MR refractory to medical management. Repeat cardiac catheterization revealed stenosis of the right proximal coronary artery, raising concern for progressive coronary involvement. In addition to dysmorphic features and failure to thrive, there were profound developmental delays and a finding of vacuolated lymphocytes on blood smear, which led to a diagnosis of mucolipidosis II (Inclusion [I]-cell disease). The patient was referred for mitral valve replacement, which was successful; however, ongoing respiratory issues attributed to the progression of I-cell disease led to a prolonged hospitalization with placement of a tracheostomy. Reports of coronary anomalies in patients with I-cell disease are rare. An association between mucopolysaccharidosis syndromes and coronary artery abnormalities has been established and is supported by this case report, highlighting the importance of considering the potential for coronary artery involvement with I-cell disease and other similar storage diseases.