Cone-Rod Dystrophy 1

CRD1 causes early-onset retinal degeneration in American Staffordshire Terriers. Those with two copies of the mutated gene will experience severe visual impairment in early adulthood. The condition is autosomal recessive, meaning both parents must be carriers for the offspring to be affected. Dogs with one normal and one CRD1 gene are carriers but don't show symptoms.