GenotypicandallelicfrequencyofamutationintheNHEJ1 gene associated with collie eye anomaly in dogs in Italy

Abstract

Background: A7.8-kbdeletioninintron4oftheNHEJ1 canine gene is associated with Collie Eye Anomaly (CEA). This deletion has been described in sheep-herding breeds related to the collie lineage and in several other dog breeds. A genetic test based on this association can distinguish three genotypes: normal, carrier and affected. The present study is a retrospective investigation of the presence of the CEA allele frequencies in selected breeds from the Italian dog population over a 10-year time span. Methods: Genotype data, for the 7.8 kb deletion in intron 4 of the NHEJ1 gene, from 496 dogs belonging to Border collie (BC, n = 334), Shetland Sheepdog (SS, n = 74), Australian Shepherd (AS, n = 52), Nova Scotia Duck Tolling Retriever (NS, n = 20) and Rough Collie (RC, n = 16) were analysed. The genetic frequency of CEA allele was estimatedinbreedswithhigherobservations(BC,SSandAS). Results: Healthy carriers were 50%, 45%, 29.6%, 17.3% and 12.5% in SS, NS, BC, AS and RC,respectively.Theaffectedrecessivehomozygoteswere81.3%,10.8%and1.5%inRC, SS and BC, respectively. The CEA allelic frequencies were 0.36, 0.16 and 0.087 in SS, BC and AS, respectively. Conclusion: The results support the usefulness of this type of genetic analysis to optimize the care of dogs where the CEA mutation is present, including assessing the health risktosusceptibledogswithinabreedandtoprovideanobjectivebasisforbreeding programmes.