Genetic mutation gives cats a 'salty liquorice' coat colour

A new coat colour pattern has emerged in cats across Finland, and scientists have just identified the genetic mutation responsible for it.

The fur on the backs of these cats is coloured only at the base near the skin. Each hair progressively gets whiter towards the tip, and the tips of their tails are usually white as well. Otherwise, the cats share the classic “tuxedo” pattern that features an all-white neck, chest, belly and paws – although spots of colour sometimes cover parts of the white markings, says Heidi Anderson at Mars Petcare Science & Diagnostics in Helsinki.

Anderson and her colleagues have dubbed the new coat “salmiak” because the colouring resembles that of the popular Finnish salty liquorice of that name, she says.

People first noticed the unusual fur patterns – which became known originally as “the Finnish mutation” – in three cats in central Finland in 2007. In 2019, researchers at the University of Helsinki reached out to Anderson, a specialist in feline genetics, after learning about another “Finnish mutation” cat.

Together, the researchers sought out more such cats throughout Finland via media announcements, says Anderson. When DNA testing on the cats turned out to be negative for all the gene variants already known to affect white colouring in cat coats, the researchers decided to dig deeper.

They sequenced the entire genome of two of the cats and found a mutation at a chromosome site very close to the KIT gene, which is associated with various white hair patterns in many domestic animal species. “There was a huge chunk of sequence missing downstream from the KIT gene,” says Anderson.

The researchers then created a specific test for the newly discovered variant to confirm that it was responsible for the fur pattern. Out of the 181 additional Finnish house cats they tested, only three had salmiak coats – and each of these had inherited the variant from both of its parents. Another three cats had inherited the variant from a single parent, and the remaining 175 didn’t have the variant at all.

The findings confirm that the team has identified the recessive mutation that leads to salmiak fur, says Anderson. “These coats have aroused a lot of admiration for years,” she says. “It’s really exciting that we now have some genetic explanation for it.”