The genetic basis for a striking new coat color – known as ‘salmiac’ – 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 from the University of Helsinki and the company Wisdom Panel has identified the genetic mutation responsible for a new, distinctive coat color pattern that recently emerged in domestic cats in Finland. Originally known as ‘the Finnish mutation’ when it was first noted in 2007, this coat color is found in only one population of feral cats characterized by their black and white ‘tuxedo’ coat pattern. But this new coat color pattern is unique because the coat is only colored near the base and becomes progressively whiter along its length. These cats also have white tail tips.
This color pattern was called “salmiak”, after the salty licorice variety popular in Finland.
Salmiak cats usually have the classic “tuxedo” pattern with an all-white neck, chest, belly and paws – although patches 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 cat genetics and molecular diagnostics. Dr. Anderson is also a scientific advisor at the EveryCAT Health Foundation.
Salmiak colors a domestic cat (Credit: Ari Kankainen / Wisdom Panel)
Fascinated by the appearance of these cats and in possession of a genetic sample, researchers from the University of Helsinki contacted Dr. Anderson and the Wisdom Panel team for help identifying the genetic origins of this distinctive coat color and to better understand its genetics.
“Since the first sighting, cats with this color pattern have remained a rare sight in central Finland,” wrote Dr. Anderson in a blog post. “They are descended from the same wild population, and only non-pedigreed cats are known to have this coat pattern.”
Dr. Anderson and his collaborators began their study by genotyping a salmia cat for possible coat color gene variants using the MyCatDNATM panel screening test. This test showed that there was no known genetic explanation for the white hairs of the salmia cat. Dr. Anderson and his collaborators then genotyped more salmia cats with the MyCatDNA panel test and again discovered that their atypical white patterns had a new and unidentified (at the time) genetic background.
Considering that white coat patterns in animals are due to variants in the KIT gene, Dr. Anderson and collaborators identified this gene as a good focus point for a more detailed investigation into the genetics underlying this recently discovered white coat 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 associated with piebaldism have been identified. In horses, a group of genetically related coat color variants are identified as coat mutations KIT gene are known as ‘dominant white’.
In both pedigree and non-pedigree domestic cats, the white color is largely explained by two common variants of the KIT gene (also known as Whiteor W place). In addition, the breed-defining white paws in Birman cats are associated with another variant in the KIT gene. Dr. So Anderson and his associates had a good reason to suspect the cause KIT gene as the most likely candidate locus for this newly discovered white coat pattern.
But the first sequence of two salmia cats KIT genes revealed none variants. To further investigate the source of this characteristic coloration, Dr. Anderson and co-workers performed whole-genome sequencing on samples from two salmia cats. Again, no KIT variants. But when Dr. Anderson and associates surveyed the region KIT gene, they discovered a fairly large deletion – 95,000 base pairs – downstream of the KIT gene in both sal ammoniac cats – and realized that this deletion could potentially have an impact KIT gene expression (Figure 2).
FIGURE 2: Schematic representation of the newly identified wsal allele of the KIT locus. a … [+]
To confirm their findings, Dr. Anderson and his collaborators genotyped another 180 Finnish domestic cats, along with three more salmia cats. They found that the three salmiak cats had two copies of the gene mutation, while three others had only one copy of the mutation – but they lacked the salmiak coat color. This confirmed that the sal ammoniac color pattern is recessively inherited, meaning the trait is only visible if the cat has two copies of the mutation, one from each parent.
Although uncommon, such a genetic deletion has previously been identified in a variety of animals. A structural mutation previously found downstream of the KIT gene is associated with the white coat color in cattle, goats and horses.
“The discovery of the sal ammoniac variant enriches our understanding of the genetics of cat coat color,” noted Dr. Anderson op.
“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 cat 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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