New marker found for Sanfilippo disease

Sanfilippo disease is a rare disorder caused by the failure of enzymes to break down specific kinds of complex carbohydrates, resulting in their accumulation in cells and often severe physical and neurological problems – and sometimes early death.

In a paper published in the March 4 issue of the Journal of Biological Chemistry, researchers at the University of California, San Diego School of Medicine, led by Jeffrey D. Esko, PhD, professor in the Department of Cellular and Molecular Medicine, describe the build-up of a novel secondary metabolite in Sanfilippo disease, a discovery that could improve understanding of the disease's pathology and refine diagnostic techniques.

Sanfilippo is one of a group of genetically inherited metabolic disorders called mucopolysaccharidoses, all of which involve the inability of different lysosomal enzymes to catabolize or break down glycosaminoglycans – complex sugar carbohydrates that help cells build skin, bone, cartilage, tendons and connective tissues.

''It's a very ordered sequence of degradation,'' said Esko, co-director of the Glycobiology Research and Training Center at UC San Diego. ''Interference with any of the steps in the enzymatic process results in an accumulation of metabolites, which causes lyosomal dysfunction. Cells become constipated, leading to internal changes and dysfunction.''

For patients with severe mucopolysaccharidosis, the consequences can be catastrophic. As incompletely degraded glycosaminoglycans accumulate in cells and tissues, they cause permanent, progressive damage that affects appearance, physical abilities, organ function and, most profoundly, mental development.

Children with the disease can experience severe neuropathology and significant early mortality. It's estimated that 1 in 25,000 children in the United States have one of several forms of the disease. Some mucopolysaccharidoses can be temporarily treated with enzyme replacement therapies, but the body's blood-brain barrier blocks neurological benefit. There is no current cure.