Dogs are descended from wolves, but in the process of domestication their look and behaviour have been modified, and so have their genes.
Dogs Descended From Wolves
Some wolves had become dogs at least 15,000 years ago, but exactly how this domestication came about is not clear.
Different Dog Breeds
All dogs are the same subspecies of the Grey Wolf – all dogs are classified scientifically as Canis lupus familiaris. Within this subspecies there are many (thousands) of distinct types known as ‘breeds’ of dog.
There are thought to be around 400 million dogs in the world, and there is more variation in size, appearance, and behavior between dog breeds than there is in any other domestic animal, for example size ranges from a few inches (Chihuahua) to a few feet (Irish Wolfhound).
The study of the genetics of some dog breeds has helped people understand the genetics of certain human genetic disorders.
Dog Genes and Human Genetic Disorders
The genes that cause the particular characteristics of some dog breeds have been identified, and in a few cases the same gene has been found to be present in humans with a genetic disorder. Two examples will suffice:
The Rhodesian Ridgeback has duplications in the fibroblast growth factor genes FGF3, FGF4 and FGF19. This gives the breed its characteristic ‘ridge-back’. In humans it has been found that mutations in the genes encoding certain FGFs cause cleft palate, while mutations in FGFR2 have been linked to spina bifida.
In Boxers the MITF gene, that helps control the development and function of pigment-producing cells, is also important for hearing. White Boxers are frequently deaf. In humans mutations of the MITF gene cause pigment changes and loss of hearing (Waardenburg syndrome type 2).
Further studies of dog genetics are likely to shed light on a range of human genetic problems.