Washington, Aug 29 - Data from Portuguese water dogs, one of which is owned by US President Barack Obama, helped researchers identify a gene that gives some canines curly hair and others long, wavy hair.

It was part of a National Institute of Health (NIH) study showing that variations in only three genes account for the seven major types of coat seen in purebred dogs.

The findings also point towards understanding complex human diseases caused by multiple genes, says an University of Utah (U-U) release.

'We were part of a team that found three genes that control 90 percent of the seven coat types that characterise different breeds of purebred dogs,' said K. Gordon Lark, one of the 20 study co-authors and professor emeritus of biology at U-U.

'We helped identify the gene that controls curly or wavy coats,' adds study co-author Kevin Chase, a U-U research specialist in biology.

The study published was published online in the journal Science.