Collie eye anomaly: A review

Abstract

Collie eye anomaly (CEA) is an inherited congenital visual impairment with heterogeneous signs. The first symptoms are already visible in the early embryo. Among the most affected breeds are Collies and Shetland Sheepdogs but the disease has spread to different breeds depending on the country of origin. Dogs affected with this disease share a 7.8 kb deletion in intron 4 of the NHEJ1 gene. Inheritance of this disease is autosomal recessive with incomplete penetrance. Thanks to a commercially available genetic test breeders can identify genetically affected recessive homozygotes and clinically healthy but genetic carriers of the mutation and thus select healthy parents for the next generation of dogs. However, the exact cause of the disease is not known and it is not known whether the causative mutation influences the occurrence of some other diseases (e.g. immunodeficiencies).