Mucopolysaccharidosis Type I is one of a group of eleven different genetic diseases known as the MPS disorders. The MPS disorders are all classified as lysosomal storage diseases. Signs include tremor, difficulty balancing and walking, head tilts, falling, generalized balance problems, growth retardation, corneal clouding leading to visual impairment, and lameness. The disease is progressive. Age of onset varies, but normally early adulthood. The clinical signs in the dogs have been reported to appear between 2-4 years of age. Dogs euthanized usually within 1-2 years after onset of clincial signs. May be associated with changes to coat colour, but this is unconfirmed at time of writing.