Purpose
To characterize the microscopic and ultrastructural morphology of the anterior uvea of Beagles with autosomal recessively inherited POAG due to a G661R missense mutation in the ADAMTS10 gene.
Methods
Four animals were analyzed, a 6-month old (6m-/+) and a 3-year old (3y-/+) non-affected dog heterozygous for ADAMTS10 mutation, and two age-matched affected dogs homozygous for the mutation (6m-/-; 3y-/-G); the older affected dog showed clinical signs of glaucoma. Animals were enucleated and globes processed for histology and transmission electron microscopy (TEM).
Results
Grossly the 3y-/-G animal presented markedly irregular ciliary processes. Both homozygous animals presented with thick and homogenous eosinophilic, PAS-positive and Masson’s trichrome blue, proteinaceous material carpeting the ciliary body surface, consistent with collapsed dysplastic zonular ligaments. TEM showed a thick mat of dysplastic zonular ligament fibrils associated with markedly irregular and reduplicated basement membranes carpeting the surface of the ciliary body epithelium. The 3y-/-G animal also presented moderate disruption of the collagen fibers in the core of the trabecular meshwork beams. All animals presented normal scleral collagen.
Conclusions
The lesions are consistent with previously described zonular ligament dysplasia of terrier dog breeds affected by a mutation in ADAMTS17. Mutations in both ADAMTS10 and ADAMTS17 are responsible human Weill-Marchesani syndrome. The zonular and TM collagen lesions suggest the mutation impacts the metabolism of these proteins in the ocular tissues. Histological and TEM features of the trabecular meshwork are compatible with POAG and support the use of these animals as POAG model.
Keywords: 421 anterior segment •
455 ciliary body •
637 pathology: experimental