PRAstands for Progressive Retinal Atrophy. Progressive means that continues. The retina is the retinal atrophy, and is a process that breaks down slightly (degenerate). PRA is the collective name for a group of disorders which are all responsible for the degenerate (break) of the retina. In the retina there are light-sensitive cells, the rods and cones. These cells make it possible to see. If these rods and cones are damaged, the dogs view will grew worse. If all rods and cones are completely atrophied than the dog is completely blind. PRA is a condition that is genetically determined. The condition is "single autosomal recessive". Autosomal means that the disease is not sex-linked. Singular means that a genetic trait is responsible for the disorder. Recessive means that this characteristic for the disorder is to be obtained from both parents. If one of the parents does not have the property, the puppies will not be sick, but they may have the property of the disease in their genes.
Lopra stands for Late Onset Progressive Retinal Atrophy
Rcd-4 stands for rod-cone (rod-cone) degeneration 4
Free:these dogs have two normal copies of the DNA. They cannot develop LOPRA RCD-4 due to the RCD-4 mutation. But they can still develop a different kind of PRA due to other mutations.
Carrier: these dogs have one copy of the mutation and one normal copy of the DNA. They cannot develop LOPRA RCD-4 due to the RCD-4 mutation but they give the mutation by about 50% of their offspring. They can still develop a different kind of PRA due to other mutations.
Affected:these dogs have two copies of the RCD-4 mutation and LOPRA RCD-4 can develop during their lives.