Genetic Mutations Identified in English Shepherds
Other genetic diseases recently discovered in English Shepherds include Collie Eye Anomaly (CEA), Progressive Retinal Atrophy – Progressive rod-cone degeneration (PRA-prcd), a few carriers of Hyperuricosuria (HU), and possibly Degenerative Myelopathy (DM).
No cases of Degenerative Myelopathy have been diagnosed in the breed though a few dogs have tested to be carriers of a mutation associated with risk for DM. There is some thought that the gene being tested for may only indicate a susceptibility to the disease, and that another gene or genes actually determine if the disease ever develops. More work needs to be done to clarify how this disease is passed on.
Collie eye anomaly produces a malformation in the eye that can make a dog blind. The degree of seriousness varies widely, even in affected dogs (genotype=mutant/mutant), so that they may have perfectly normal vision, or they could go blind as puppies. CEA can be diagnosed in young puppies (< 6 weeks) by looking at the retina and optic nerve connection in the dog’s eye.
Progressive retinal atrophy is a gradual degeneration of the rods followed by the cones in the eye. Symptoms usually begin around five years of age. Rods degenerate first, and that leads to night blindness. Then the cones degenerate until the dog is blind.
MDR1, as well as other genetic diseases, can be tested for. Below are portions of reports for DNA tests for two English shepherds, showing that one is not a carrier for MDR1, CEA, or PRA-prcd, the other is not a carrier of MDR1, but does carry CEA. Neither dog is affected by either disease.
This canine’s DNA showed the following genotype(s):
Disease Gene Genotype Interpretation
Collie eye anomaly NHEJ1 WT/WT Normal
Multidrug resistance 1 ABCB1 WT/WT Normal
Progressive retinal atrophy,
Progressive rod-cone degeneration PRCD WT/WT Normal
Another dog:
This canine’s DNA showed the following genotype(s):
Collie eye anomaly NHEJ1 WT/M Carrier
Multidrug resistance 1 ABCB1 WT/WT Normal
Progressive retinal atrophy,
Progressive rod-cone degeneration PRCD WT/WT Normal
NOTE: WT = wild type (normal); M = mutant
Hyperuricosuria is a disease that predisposes a dog to have elevated levels of uric acid in the urine, which can result in stones, urinary tract infections, and other painful symptoms. While an actual case of hyperuricosemia has not been reported in English Shepherds, one of the genetic testing companies has found at least four carriers of this mutation in the breed.