ABSTRACT
The enormous existing variety in domestic dogs was generated through selective breeding. This process has been inexact: selection for some traits has also led to increased prevalence of undesired traits, such as predisposition to specific diseases. My chapter explores the potential use of “gene repair”: a process of gene editing that replaces a deleterious gene with one that is naturally found in that species and that functions normally. Currently, if we identify specific mutations in dogs that cause or predispose disease, we can exclude individuals carrying these genes from future breeding. This risks further limiting the gene pool and having other deleterious traits become fixed in the population. With CRISPR-Cas9, we can attempt to repair these genes specifically and preserve the rest of the genetic diversity contained within that individual. Gene repair in dogs could provide significant medical benefits for both dogs and humans. We could also consider potential applications of CRISPR to endangered wild animals. Here, I distinguish between gene repair using a normal gene from that species versus inserting a gene from another species to confer new traits. Such efforts carry risk, as cascading impacts throughout an ecosystem could result from unpredictable changes in the species being manipulated. The “One Health” approach to medicine teaches us that human health depends on the health of nonhumans and the environment, and the first rule of medicine is “do no harm.”
