GUSB and mucopolysaccharidosis type 7: Mucopolysaccharidosis (MPS) VII (also known as Sly syndrome) is an ultra‐rare, autosomal recessive, debilitating, and life‐threatening lysosomal disease caused by a deficiency of the β‐glucuronidase (GUSB) enzyme that aids in the degradation of glycosoaminoglycans (GAGs).1, 2 As a result, GAGs such as dermatan, chondroitin, and heparan sulfate, accumulate in a wide variety of tissues and cause organ dysfunction.