Completed Grant No. 1870:     Genetics of Hereditary Deafness in the Domestic Dog

Researcher: Keith E. Murphy, PhD, Texas A&M University

Program Area: Prevention

Sponsor(s): Dalmatian Club of America Foundation, Inc., English Setter Association of America, Random Individuals

Project Dates: 9/9/1999 to 9/8/2002

Grant Amount: $77,000.00

DCAF Funding: $11,750.

Abstract:

• Congenital deafness has been reported for approximately 60 breeds, and can potentially appear in any breed. The disorder is usually associated with pigmentation patterns, where increasing amounts of white in the hair coat increase the likelihood of deafness. Pigment-associated inheritance of deafness is not restricted to dogs. Similar defects have been reported for mice, mink, pigs, horses, cattle, cats and humans. Waardenburg syndrome type 2 (WS2) in humans presents with congenital deafness and hypopigmentation of the eyes and head hair.
  This is an autosomal dominant disorder with incomplete penetrance, meaning that individuals that inherit the disorder may not show all of the components of the syndrome. Mutations in the mitf gene cause at least twenty percent of cases of WS2. Piebaldism in humans most commonly presents with congenital patches of white skin and hair-lacking melanocytes on certain parts of the body, although deafness is a characteristic of the disorder in an unknown percentage of affected individuals. Mutations in the kit gene are responsible for typical cases of piebaldisms. We believe that deafness is dogs may result from mutations in the canine mitf/kit genes. Examination of these genes and identification of causative mutations will aid in understanding the etiology of deafness.