Glossary

A number of breeds are known to suffer from hereditary cataract and there are almost certainly different genetic causes for a number of these. Mutations in one gene called HSF4, has been shown to cause hereditary cataract in a number of different breeds (Australian Shepherd, Boston Terrier, French Bulldog and Staffordshire Bull Terrier). One of the HSF4 mutations causes bilateral cataracts, in Staffordshire Bull Terriers, Boston Terriers and French Bulldogs, that can be diagnosed as early as 8-12 weeks of age, but are not congenital. Obvious cataracts occur between 9 and 15 months of age with further progression and maturity of the cataract between 2-4 years. This is a blinding condition if left untreated. In these breeds the mutation in HSF4 is a recessive mutation and so an affected dog must have two copies of the mutation, one inherited from the dam and the other from the sire, before it will develop cataracts. A slightly different mutation in the same gene has been identified as a risk factor for bilateral posterior polar subcapsular cataracts in the Australian Shepherd. This form of cataract has quite a variable age of onset and in this breed, the HSF4 mutation appears to behave as a co-dominant or dominant mutation, so an affected dog need only inherit one mutant copy to be at increased risk of developing this form of cataract.

Source of DNA Test: http://www.thekennelclub.org.uk/download/8288/dnatestsworldwide.pdf