The genetic basis for a distinctive new coat coloring — known as “salmiak” — has been identified in domestic cats in Finland
Swedish salty liquorice “Djungelvrål” (in English: roar of the jungle). (Credit: Marcin Floryan / CC … [+]
Oh, this is fun: a collaboration of scientists at the University of Helsinki and at the company Wisdom Panel, have identified the genetic mutation responsible for a new, distinctive coat color pattern that arose recently in domestic cats in Finland. Originally known as “the Finnish mutation” when it was first spotted in 2007, this coat color is found in just a single feral cat population that is characterized by their black-and-white “tuxedo” coat pattern. But this new coat color pattern is unique because the fur is colored only near the base, and becomes progressively whiter along its length. These cats also have white tail tips.
This color pattern was named “salmiak” after the variety of salty liquorice that is popular in Finland.
Salmiak cats tend to have the classic “tuxedo” pattern with an all-white neck, chest, belly and paws — although spots of color sometimes cover parts of the white markings, according to Heidi Anderson, a senior scientist at Wisdom Panel (formerly Mars Veterinary/Wisdom Health) based in Helsinki, where she specializes in feline genetics and molecular diagnostics. Dr. Anderson also serves as a Scientific Advisor at EveryCAT Health Foundation.
Salmiak coloring in a domestic cat (Credit: Ari Kankainen / Wisdom Panel)
Captivated by the look of these cats and in possession of a genetic sample, the University of Helsinki researchers contacted Dr. Anderson and the Wisdom Panel team for help identifying the genetic origin of this distinctive coat color and to better understand its genetics.
“Since first observed, cats with this color pattern have remained a rare sight in central Finland,” wrote Dr. Anderson in a blog post. “They descend from the same wild population, and only non-pedigreed cats are known to have this coat pattern.”
Dr. Anderson and collaborators began their investigation by genotyping a salmiak cat for potential coat color gene variants using the MyCatDNATM panel screening test. This test revealed that the white hairs in the salmiak cat had no known genetic explanation. Dr. Anderson and collaborators then genotyped additional salmiak cats with the MyCatDNA panel test and once again, found that their atypical white patterning had a novel and unidentified (at the time) genetic background.
In view of the fact that white coat patterns in animals result from variants in the KIT gene, Dr. Anderson and collaborators considered this gene to be a good focal point for a more detailed investigation into the genetics underlying this recently discovered white fur pattern.
The KIT gene is crucial for the development of many cell types, including blood and pigment cells (melanocytes). In humans, for example, at least 69 KIT gene mutations have been identified that are associated with piebaldism. In horses, a group of genetically related coat color variants identified as mutations on the KIT gene are known as “dominant white.”
In both pedigreed and non-pedigreed domestic cats, white coloring is largely explained by two common variants of the KIT gene (also known as White, or W locus). Additionally, the breed-defining white paws in Birman cats is associated with another variant in the KIT gene. So Dr. Anderson and collaborators had a good argument for suspecting the KIT gene as the most likely candidate locus for this newly discovered white fur pattern.
But initial sequencing of two salmiak cats’ KIT genes did not reveal any variants. To further investigate the source of this distinctive coloring, Dr. Anderson and collaborators performed whole-genome sequencing on samples from two salmiak cats. Again, no KIT variants. But when Dr. Anderson and collaborators inspected the region around the KIT gene, they spied a rather large deletion — 95,000 basepairs — downstream from the KIT gene in both salmiak cats — and realized this deletion could potentially impact KIT gene expression (Figure 2).
F I G U R E 2 : Schematic presentation of the newly identified wsal allele of the KIT locus. A … [+]
To confirm their findings, Dr. Anderson and collaborators genotyped an additional 180 Finnish domestic cats along with three more salmiak cats. They found that the three salmiak cats had two copies of the gene mutation, whilst three others had just one copy of the mutation — but they lacked the salmiak coat coloring. This confirmed that the salmiak color pattern is recessively inherited, meaning that the trait is only visible if the cat has two copies of the mutation, one from each parent.
Although unusual, such a genetic deletion has been identified before in a variety of animals. For example, a structural mutation previously found downstream of the KIT gene is associated with white coat color in cattle, goats and horses.
“The discovery of the salmiak variant enriches our understanding of feline coat color genetics,” Dr. Anderson pointed out.
“But that’s not all. This knowledge could also be valuable for breeding efforts, potentially contributing to the preservation of this trait in our feline companions.”
Source:
Heidi Anderson, Milla Salonen, Sari Toivola, Matthew Blades, Leslie A. Lyons, Oliver P. Forman, Marjo K. Hytönen, Hannes Lohi (2024). A new Finnish flavor of feline coat coloration, “salmiak,” is associated with a 95‐kb deletion downstream of the KIT gene, Animal Genetics | doi:10.1111/age.13438
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Dr. Thomas Hughes is a UK-based scientist and science communicator who makes complex topics accessible to readers. His articles explore breakthroughs in various scientific disciplines, from space exploration to cutting-edge research.
