Sylvester Sanfilippo (January 1, 1926 – May 2, 2013) was a pediatrician from Edina, Minnesota, who first described a mucopolysaccharide storage disease which bears his name. Sanfilippo was born in Rochester, New York. After graduating from the University of Rochester in 1947, he moved to Salt Lake City to pursue postgraduate studies. There he received a Master of Science degree in Biochemistry and earned his medical degree in 1955. He acquired his pediatric training at the University of Minnesota, interrupted by a two-year stint as a pediatrician in the United States Navy Medical Corps in Portsmouth and Norfolk, Virginia.
In 1960 Sanfilippo was awarded a postdoctoral research fellowship and began a comprehensive study of children with mucopolysaccharide storage disease at the University of Minnesota. The investigative approach combined the chemical measurement and identification of urinary acid mucopolysaccharides with a thorough clinical evaluation of each patient.
The work of Sanfilippo and his colleagues described eight mentally challenged children with mucopolysacchariduria of a single compound, heparitin sulfate. In contrast, their thirteen patients with Hunter–Hurler syndrome showed mucopolysacchariduria of two compounds, heparitin sulfate and chondroitin sulfate B. The majority of the heparitin sulfate excretors had a normal or near-normal facial appearance and displayed mild to slight somatic and radiographic manifestations in comparison with their Hunter–Hurler counterparts, who showed more severe involvement. These observations indicated the existence of a new inborn error of the mucopolysaccharide metabolism.