Pedigree of a dog breed affected with Progressive Retinal Atrophy (PRA). Courtesy of Jesús Aguirre-Hernández, Centre for Veterinary Science, University of Cambridge.

In this particular breed the disease is recessive, and it has a very early onset. The first symptoms of the disease appear within weeks after the animals are born, and after a few months they are completely blind. Since the disease has a very early onset, it has been possible to take out of the breeding population those animals showing symptoms of it. However, many relatives may still carry the mutation in a heterozygous state, so it is necessary to identify the mutation in order to develop diagnostic tests that may enable to distinguish those individuals that still carry one copy of the mutation.

Affected individuals are shown in red; carriers are in yellow. Boxes are males, circles are females and hexagons are animals for which the gender is unknown. This pedigree comprises 551 individuals. aiSee makes it possible to explore different aspects of the pedigree. For example, in order to show the ancestors for one, or a few individuals, the exclusive region function is very useful (see screenshot). When it is necessary to show the particular subgraph formed by the closest relatives of a given individual, the neighbor function can do the work (see screenshot).