Sly syndrome, also called mucopolysaccharidosis type VII (MPS-VII), is an autosomal recessive lysosomal storage disease caused by a deficiency of the enzyme β-glucuronidase.

People with Sly syndrome may also have sleep apnea, frequent lung infections, and problems with vision secondary to cloudy corneas.

These can include short stature, joint deformities, dysostosis multiplex, spinal stenosis, and carpal tunnel syndrome.

[2] Vestronidase alfa-vjbk (trade name Mepsevii), an enzyme replacement therapy which is a recombinant form of human β-glucuronidase, is approved by U.S. Food and Drug Administration for the treatment of Sly syndrome.

[2] It was named after its discoverer William S. Sly, an American biochemist who has spent nearly his entire academic career at Saint Louis University.