Using a genome-wide association study we mapped the disease to a ∼13-Mb region of Canis lupus familiaris chromosome 6 (CFA6) and subsequent targeted next-generation sequencing (NGS) identified a novel missense mutation in the affected puppies in the β-glucuronidase (GUSB) gene, which causes MPS VII. Here, GUSB is linked to mucopolysaccharidosis type 7.