Dogs’ Coats Differ Due To Only Three Genes

Recent research has proven that three distinct genes are responsible for the different types of coats on dogs. Thanks to this research, a method has now been devised to identify gene combinations that are helpful for studies of human diseases.

The fact that a mere three genes can make a dog’s coat different from another dog is quite remarkable. It seems that when these three genes act in different combinations, they can cause one dog to have short hair whilst, in another combination, they can cause a different breed of dog to have curly hair.

The Research Study

Researchers from the National Human Genome Research Institute (NHGRI), which is part of the National Institutes of Health, released their findings in the online issue of the Journal Science.

The Scientific Director at NHGRI, Eric Green, M.D., Ph.D., says:

“This study is an elegant example of using genomic techniques to unravel the genetic basis of biological diversity. Genomics continues to gain new insights from the amazing morphological differences seen across the canine species, including many that give clues about human biology and disease.”

Prior to this study being performed, very little information was known about how exactly a dog’s genes affected the growth pattern, texture and length of their coats. One thousand dogs covering 80 different breeds were utilized in this study, in which the researchers conducted a genome-wide scan of specific indications of any variation in the DNA, which is called single-nucleotide polymorphisms.

The researchers then compared the descriptions of the dogs various coats with the collected data. It then became quite apparent that three very specific genetic variants existed which would explain all the different dog coats and hair types.

“What’s important for human health is the way we found the genes involved in dog coats and figured out how they work together, rather than the genes themselves,” said Elaine A. Ostrander, Ph.D., who is the chief of the Cancer Genetics Branch in NHGRI’s Division of Intramural Research. “We think this approach will help pinpoint multiple genes involved in complex human conditions, such as cancer, heart disease, diabetes and obesity.”

Selective Dog Breeding

Over the past few decades, dog breeders have started to breed specific dogs in order to acquire specific traits. The results of these breeding attempts have caused certain traits, such as hair, to become rather unique to that particular breed of dog.

It is very interesting to note, however, that the genetic changes in the dog genome, that helps to produce so many different varieties of hair types in dogs, was actually created by specific trait breeding over the previous 200 years rather than being assumed as a result of today’s dog breeds having deviated from the wolf almost 15,000 years ago.

Dogs who have very short and straight hair, like the Beagle, actually exhibit the more original wolf-like versions of those three genes that were identified in the study.

Because today’s dog has been selectively bred for so long, they have become part of a very distinctive population structure. Using this structure, the researchers were able to divide a rather complicated phenotype, the dogs’ coat, into a variety of different genetic variations.

Dr. Ostrander said:

“When we put these genetic variants back together in different combinations, we found that we could create most of the coat varieties seen in what is among the most diverse species in the world, the dog. If we can decipher the genetic basis for a complex trait such as the dog’s coat, we believe that we can do it as well with complex diseases.”

The Three Genes

The different genes were the RSPO2, FGF5, and the KRT71. The first gene, RSPO2, helps to make a dogs’ hair wiry as it grows in a unique pattern that allows for long details called furnishings. Irish and Scottish Terriers are great examples of dogs for whom the RSPO2 gene is more predominant.

Pomeranians and Cocker Spaniels have the FGF5 gene to thank for their long and silky hair.

Whilst the Irish water spaniel has more of the KRT71 gene which causes it to have a curly coat.

But dogs, such as the Portuguese water dog, who have long and curly coats with furnishings, have all three of these genes present in their DNA.

In addition to dogs, the long hair gene (FGF5) and the curly hair gene (KRT71) have also affected their hair type of cats and mice. Therefore, scientists, are speculating, these two genes might also have an effect on humans as well.

Although the third gene has been linked with the coarse hair type found in some people of East Asian ancestry, it has never before been found to influence the hair texture in mammals.

Photo Credit: La Sequencia

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