Figure 1.

Pedigree shows consanguineous familial relationships for the two 2 affected Shiba Inu, Dog A and Dog B. The dog marked with an asterisk contributed genetic material to both parents of both affected dogs. Bold lines show the shortest possible pathway for the inheritance of the causal allele from an ancestor to the homozygous affected dogs. Nonetheless, we do not have DNA from the ancestors to verify this pathway, and additional consanguineous relationships among earlier ancestors are likely. Thus, Dog A and Dog B may have obtained their homozygous mutant allele by alternative inheritance pathways.