Hurler syndrome, also known as gargoylism or mucopolysaccharidosis I-H, is a rare autosomal dominant lysosomal storage disease caused by deficiency of α-L-iduronidase, leading to accumulation of glycosaminoglycans within lysosomes and thereby causing multiorgan system disease. Within α-L-iduronidase deficiency are two types, Hurler syndrome, which is associated with a more severe phenotype, and Scheie syndrome, a more attenuated phenotype. In both phenotypes, patients have a complete lack of α-L-iduronidase enzyme activity.

Classic findings in this disease include characteristic facies, short stature, cardiomyopathy and valvular disease, hearing loss, respiratory insufficiency, and stiff joints, among others. Degree of neurologic impairment is highly variable. A spectrum from normal intellect to severe intellectual impairment has been reported.

Hurler syndrome is a chronic progressive disease. Those with severe phenotypes often do not survive the first decade of life; milder phenotypes can survive into adulthood with significant morbidity.