Primary Lens Luxation (PLL)

Primary Lens Luxation (PLL) is a painful inherited eye disorder where the lens of the eye moves from its normal position causing inflammation and glaucoma. PLL results from a single base change mutation in the gene ADAMST17 (ADAMTS17:c.1473+1). If untreated, the condition can rapidly lead to blindness.

The study identifying this ADAMTS17 disease variant looked at 196 dogs from three different breeds (Jack Russell Terrier, Miniature Bull Terrier and Lancashire Heeler) that had been clinically diagnosed with PLL and found that 161 of them had two copies of this variant. Further RNA analysis showed that this ADAMTS17 variant resulted in a truncated transcript that was abnormal. Combined, these findings showed a strong association between the ADAMTS17:c.1473+1 variant and PLL in all three studied breeds. A subsequent study later identified this ADAMTS17 variant in PLL-affected dogs of various other breeds. However, 12 dogs diagnosed with PLL in the original study did not have this disease variant, indicating that while this ADAMTS17 variant is a common cause for PLL in several dog breeds, it is not the only one. 

The disease is inherited in an autosomal recessive fashion thus both sexes are equally affected. PLL appears spontaneously, typically between 3-8 years, although both eyes are not necessarily affected at the same time. Watery, red, teary eyes may indicate that lens luxation has occurred and veterinary intervention is required. Dogs with only one copy of the disease mutation most frequently show no sign of the disease but can, on occasion, develop PLL. Breeding between two carriers is expected to produce 25% affected offspring.

Testing for PLL assists owners and breeders in identifying affected and carrier dogs. Breeders can use results from the test as a tool for selection of mating pairs to avoid producing affected dogs.