Progressive Retinal Atrophy (PRA) refers to a group of inherited blinding canine diseases. Depending on the mutation the blindness develops faster or slower. A large number of varieties of PRA are currently known to affect several breeds. (Scientific) research is continuously developing new tests.
Test specific information
This test is performed by OPTIGEN.
In collaboration with Drs. Doreen Becker and Gus Aguirre at the University of Pennsylvania, OptiGen’s R&D scientists, have discovered a new genetic variant that explains a large portion of PRA cases in the Miniature Schnauzer. Based on that discovery, OptiGen now offers a genetic test called Type B PRA test for Miniature Schnauzers. This DNA test is able to identify dogs that carry zero, one or two copies of the Type B PRA risk variant.
‘Early onset’ – This phrase indicates, that the symptoms of the disease can be detected at a lower age. ‘Early onset’ is the opposite of ‘late onset’, in which symptoms may be present at later ages. The phrases are used because the mutation causing ´early onset´ symptoms may be different compared to the mutations causing ´late onset´ symptoms.
Turn Around Time
The turn-around-time of a test depends to a large extent on the logistics of sample transportation to the laboratory. After receiving the sample at the test location, you can normally expect the result within 10 working days. A longer delivery time applies to tests carried out by a Partner Lab.
Location of disease or trait
This disease mainly affects vision, and may result in blindness.
This DNA test is available for the following breeds: Miniature Schnauzer. Additional information is available in the Frequently Asked Questions (FAQ).
For this DNA test we accept the following materials: Blood EDTA, Blood Heparin, Semen, Swab, Tissue. Please contact Dr. Van Haeringen Laboratorium if you wish to submit other material as listed.
• Homozygous wild type/Clear: the dog carries NO copies of the risk variant; will not develop Type B PRA
• Heterozygous/Carrier Risk Variant: the dog carries ONE copy of the risk variant; will not develop Type B PRA
• Homozygous Risk Variant: the dog carries TWO copies of the risk variant; at high risk of developing Type B PRA
The Type B PRA test results are reported as Risk Variants because, although dogs carrying two copies of the variant are very likely to develop PRA, a subset (14%) of the research sample set that were homozygous for the variant did not develop PRA by 7 years of age. It is not clear at this time whether the variant represents a causal mutation –and that other factors influence the “penetrance” of the mutation—i.e. its ability to cause disease-- or if the variant is a genetic marker that resides near the causal mutation. OptiGen and the University of Pennsylvania scientists will continue research aimed at better understanding this question.
Dogs that are Homozygous Risk Variant for Type B PRA have a high risk of developing Type B PRA. Within the research sample set, these dogs had an 86% chance of developing PRA, based on the initial research group of 108 genotyped dogs.
This genetic factor is inherited in an autosomal, recessive, mode. This means, that the individual can be free of the disease (homozygote normal), affected (homozygous affected) or carrier (heterozygous).
Carriers may spread the mutation in a population without showing symptoms themselves. Because of this, it is extremely important to identify carriers correctly to prevent spreading of a mutation.
Severity of Disease