POAG -PLL Shar Pei Type
POAG-PLL Shar Pei type are two different ocular neuropaties caused by same mutation in the same gene. Primary open angle glaucoma (POAG) is a hereditary eye disorder which causes build up of intraocular pressure, and primary lens luxation (PLL) is characterized by lens dislocation and loss of sight.
Generally, glaucoma can be divided in two different forms of the disorder, primary and secondary glaucoma. Primary glaucoma is characterized by its onset without any other ocular cause, while secondary glaucoma appears when another cause is present, which triggers the glaucoma. Primary open angle glaucoma belongs in the group of primary glaucoma together with primary angle closure glaucoma (PACG) and primary congenital glaucoma (PCG). In Shar Pei breed POAG has not been well characterized, but it appears to be open-angle rather than the closed-angle form. The disorder has been identified in several dog breeds, most of which are caused by breed-specific mutation, occuring only in that specific dog breed. Except POAG Shar Pei type, other breeds with diagnosed POAG include the Beagle, Norwegian Elkhound, Basset Hound, Basset Fauve de Bretagne and Petit Basset Griffon Vendeen.
PLL is caused by displacement of the lens as a result of stretching or rupture of the zonular fibers that link ocular lenses in place behind the pupil. The disease can be caused by trauma or by a variety of conditions that distort normal ocular anatomy, such as glaucoma and intraocular tumours. Generally, encountered at high frequency in several terrier breeds and in some other breeds with probable terrier coancestry.
POAG-PLL Shar Pei Type Genetics
POAG-PLL Shar Pei type is caused by a 6-bp deletion in ADAMTS17 gene. The disorder is inherited as an autosomal recessive disorder. Healthy parents of an affected dog are obligate heterozygotes, and therefore carry one mutant allele. Heterozygotes are carriers and show no symptoms. At conception, each cub has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier.
James A. C. Oliver, Sophie Rustidge, Louise Pettitt, Christopher A. Jenkins, Fabiana H. G. Farias, Elisabeth A. Giuliano, Cathryn S. Mellersh (2018) A novel ADAMTS17 mutation is associated with primary open angle glaucoma and primary lens luxation in the Shar Pei. Am J Vet Res. 79(1):98-106. doi: 10.2460/ajvr.79.1.98.