The genetically diverse Bo Obama

Just three genes separate the curly coat of Portuguese water dogs like the Obama family pooch, Bo, from the short-haired fur of his wolf ancestors, a study shows.

Variations in the three genes create seven types of coats, including the First Mascot's shaggy mane, according to the report published last week in the journal Science.

The canine research shows that complex traits can arise from a small number of inherited genes, which may help in studying the genetic causes of such human diseases as cancer and heart disease, according to the report.

The work gives "glimpses of how major regulatory genes interact with other genes to change the functioning of an animal," said study author Gordon Lark, an emeritus biology professor at the University of Utah, who also owns a Portuguese water dog.

The researchers don't know if these three genes influence human hair texture, though two of them - the long-hair and curly-hair genes - affect the hair of mice and cats, they said.

The researchers used 96 dachshunds, 76 Portuguese water dogs, and 903 dogs from 80 other breeds to confirm the results.

RSP02 is associated with mustaches and big eyebrows. FGF5 determines whether the dog will have long or short hair, and variation on KRT71 creates curls.

The short hair, as in basset hounds, is the "ancestral" form of all the genes, inherited from wolves.

Long-haired dogs, such as the golden retriever, have variations of FGF5 genes.

Variations on FGF5 and RSP02 create dogs such as the bearded collie, with mustaches and large eyebrows. Irish water spaniels and other curly-haired dogs have modifications on the FGF5 and KRT71 genes.

Some Portuguese water dogs, including Bo Obama, have the variant form of all three genes, Lark said.

It makes Bo quite inclusive for a presidential pooch.