Attenuated Cardiac–Ocular Phenotype of Sanfilippo Syndrome (MPS IIIA) Presenting With Hypertrophic Cardiomyopathy and Cone-Rod Dystrophy

We describe a 39-year-old woman with cone-rod dystrophy and hypertrophic obstructive cardiomyopathy complicated by an apical aneurysm, ventricular tachycardia, and ischemic stroke, ultimately requiring heart transplantation. Histopathology revealed myocardial storage vacuoles, and biochemical and genetic testing confirmed Sanfilippo syndrome type IIIA (MPS IIIA) with 1 known pathogenic and 1 novel likely pathogenic SGSH mutation. This case illustrates an attenuated cardiac–ocular phenotype of MPS IIIA and emphasizes the need to consider late-onset lysosomal storage disorders in adults with unexplained hypertrophic cardiomyopathy.