Phenotype: Juvenile hereditary cataract (JHC) affects both eyes symmetrically and has early onset, with cataract formation starting before 1 year of age and progressing to maturity and blindness by 2-3 years of age.

Mode of Inheritance: Autosomal recessive

Alleles: N = Normal, JHC = Juvenile hereditary cataract

Breeds appropriate for testing: Boston Terrier, French Bulldog, Staffordshire Bull Terrier

Explanation of Results:

• Dogs with N/N genotype do not have the juvenile hereditary cataract mutation and cannot transmit this variant to their offspring. However, cataracts may develop because of other genetic and environmental factors.

• Dogs with N/JHC genotype may not develop juvenile hereditary cataracts, but are carriers. They will transmit this juvenile hereditary cataract variant to 50% of their offspring. Matings between two carriers are predicted to produce 25% of puppies at risk for juvenile hereditary cataracts.

• Dogs with JHC/JHC genotype may develop juvenile hereditary cataracts, a condition that progresses to blindness.