New genetic research may explain why Fluffy is so fluffy.A study led by researchers at the National Human Genome Research Institute scanned 1,000 dogs from 80 breeds, looking for genes associated with different hair types: curly, wavy, straight, wiry, long and any combination of these. Their results, published online last week in Science, show that variations in just three genes account for nearly all of the different types of coats worn by man’s best friend.The study found that purebred dogs with similar hair types were found to have similar variations at three particular genes, RSPO2, FGF5 and KRT71.A particular variation in the RSPO2 gene was linked to wiry hair in a pattern that gives dogs a moustache and eyebrows, such as in a schnauzer.A variation in the FGF5 gene was associated with long hair, whether silky or fluffy, like that in a Pomeranian. Variations in the KRT71 gene seem to affect the extent of hair curl in dogs like Irish water spaniels.The FGF5 and KRT71 genes have been shown in previous studies to also affect hair type in cats and mice, suggesting that their effects may be relevant to all mammals, including humans.
Some dogs have all three of the variations identified by the researchers, including Portuguese water dogs, a breed you may have seen taking walks on the White House lawn.Short-haired dogs like beagles, who don’t exhibit any of the different types of hair studied by the researchers, all seem to have the ancestral versions of the FGF5, RSPO2 and KRT71 genes. The study also found that wolves carry the non-mutated forms of these genes, suggesting that the different types of hair evolved after the evolutionary split between the two canine subspecies.Despite what we know about the genetics of hair type in dogs, there is little known about what makes human hair straight, wavy, curly, frizzy, kinky, woolly or helical. While hair type in dogs is easily classified, studying human hair is not as simple. Some scientists have suggested characterizing hair by curl ratios and other measurements, but our diverse biological background poses a challenge in classifying human hair types for research.This study could help researchers better understand the genetics of hair type in humans. It has also unleashed new possibilities for human disease research because these three genes that affect dogs’ coats also regulate many other processes in living organisms, giving researchers a chance to study how powerful genes interact with each other.