Collie eye anomaly (CEA) *

CEA is a hereditary canine ocular disorder in which the pattern of chorioretinal and scleral development is variously disturbed. The major change, which is present in dogs with CEA, is hypoplasia (underdevelopment) of the choroid, an important layer of the eye underlaying the retina. A Coloboma, or hole, may form in or near the optic disc as part of the CEA extended phenotype. The degree of these abnormalities varies between individual dogs ranging from mild disease to complete blindness. The abnormality can be diagnosed at a very young age and is not progressive. However no treatment or cure for CEA exist. The essential features, choroidal hypoplasia and coloboma occur during eye development and become stationary in adult animals. The mutation which has been suggested to cause CEA has been published by the group of Elaine A. Ostrander at the University of Pennsylvania, USA. A 7.8 kb deletion in the NHEJ1 gene co-segregates with CEA across multiple dog breeds. This region spans a highly conserved binding domain for regulatory proteins which are required for several developmental processes.