**6. Inbreeding and disease incidence**

Inbreeding is the production of offspring from mating or breeding of individuals or organisms that are closely related [25]. It can be technically defined as mating of a pair of animals with relationship that is closer than the average level within the breed or population studied. In domesticated animals, inbreeding can decrease the performance of animals, such as decrease in milk yield, which is termed as inbreeding depression. The genetic basis of inbreeding depression is that increased homozygosity with inbreeding increases the frequency of unfavorable genotypes within the population [25]. Inbreeding can increase the incidence of inherited diseases in the population, especially those with a recessive inheritance pattern. In our studies, we estimated inbreeding coefficients using either pedigree or genome-wide genotype data. We observed significantly higher inbreeding levels in affected GLPs (average pedigree-based inbreeding: 0.23, average genotype-based inbreeding: 0.51) in comparison to those unaffected GLPs (average pedigree-based inbreeding: 0.14, average genotype-based inbreeding: 0.48). This suggests the importance of inbreeding control in preventing inherited diseases, including cancer, in pedigree dog breeding.
