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Genetic analysis of optic nerve head coloboma in the Nova Scotia Duck Tolling Retriever identifies discordance with the NHEJ 1 intronic deletion (collie eye anomaly mutation)
Author(s) -
Brown Emily A.,
Thomasy Sara M.,
Murphy Christopher J.,
Bannasch Danika L.
Publication year - 2018
Publication title -
veterinary ophthalmology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.594
H-Index - 50
eISSN - 1463-5224
pISSN - 1463-5216
DOI - 10.1111/vop.12488
Subject(s) - coloboma , biology , optic nerve , genetics , locus (genetics) , single nucleotide polymorphism , population , medicine , genotype , anatomy , gene , environmental health
Collie eye anomaly ( CEA ) encompasses a spectrum of different ophthalmic phenotypes from clinically inconsequential choroidal hypoplasia to blindness from coloboma of the optic nerve head ( ONH ). A previous study found a 7.8‐kb deletion in intron 4 of the NHEJ 1 gene to be associated with CEA . A genetic test based on this association is recommended for many breeds, including the Nova Scotia Duck Tolling Retriever ( NSDTR ). Collection of ONH coloboma‐affected NSDTR showed lack of concordance of the NHEJ 1 intronic deletion with ONH coloboma. Using genomewide single nucleotide polymorphism ( SNP ) genotyping in 7 ONH coloboma‐affected NSDTR cases and 47 unaffected NSDTR controls with no ophthalmic signs, one SNP , located on chromosome 7, demonstrated genomewide significance. However, high genomic inflation may have confounded the results. Therefore, the genomewide association study was repeated using EMMAX to control for population structure in the cohort of 7 cases and 47 controls. However, no regions of the genome were significantly associated with ONH coloboma. These results failed to document significant association with the CEA locus. Due to the complex genetic etiology of ONH coloboma, the NHEJ 1 intronic deletion test results should be carefully considered when making breeding decisions. If the goal is to select for visually competent dogs, our data suggest that eye examinations of puppies would be more effective as a guide in selection of breeding pairs than relying solely on currently available genetic tests.