Until now, the genetic basis for the orange fur coloration in cats was unknown. This pioneering research was spearheaded by geneticist Hiroyuki Sasaki at Kyushu University. The research team was able to trace this discovery to one mutation in the ARHGAP36 gene. This gene, located on the X chromosome, causes the classic orange coat. These discoveries shed light on cat genetics in groundbreaking ways. They will provide us insights into analogous genetic mechanisms in humans.
Sasaki and his collaborators carefully sequenced the genomes of 18 cats—all from the same breed—10 that were orange and 8 that weren’t. Through their research, the team discovered that all orange-coated felines had inherited the same deletion mutation in the ARHGAP36 gene. This major finding exposes how extensive the damage caused by the genetic change is. More disturbingly, it directly impacts the expression of melanogenesis genes—those that govern pigment production in our skin and hair.
Insights from The Study
The research determined that a deletion mutation affecting ARHGAP36 increases its expression by more than 310 times. This mutation decreases the expression of genes that are involved in melanogenesis. Consequently, cats with this mutation are likely to have orange coloration.
Male cats, with only one X chromosome, will have an orange coat if they inherit the orange gene. Female cats need both copies of the gene to be completely orange, making them rarer. When female cats inherit an orange gene and black gene, they typically have patchy or mottled coats, a pattern called tortoiseshell coloration. This characteristic is characteristic of calico or tortoiseshell coloration.
“These ginger and black patches form because, early in development, one X chromosome in each cell is randomly switched off,” – Hiroyuki Sasaki
Tissue taken from four of these calico cats’ skin was analyzed by the research team. They found that ARHGAP36 was much more active in melanocytes, the pigment-producing cells. This boost job was seen in physical examples harvested from orange patches, exceeding levels measured in dark or white patches. This in-depth look at the genetics behind cat coat colors and patterns certainly highlights just how intricate feline coloration can be.
Broader Implications of ARHGAP36
The importance of the ARHGAP36 gene goes well beyond cat coats. Similarly, the mutation responsible for orange pigmentation may have an important medical function in humans. This might be particularly true for conditions such as skin cancer or hair loss. Learning more about how this particular gene works may reveal new information related to these health problems.
As Sasaki aptly pointed out, the identification of such a gene was a holy grail sought by investigators in the field for decades. His team’s findings were later corroborated by an independent study conducted by researchers at Stanford University. The study further showed that an identified portion of DNA normally inhibits ARHGAP36 function when expressed.
“Identifying the gene has been a longtime dream, so it’s a joy to have finally cracked it,” – Hiroyuki Sasaki
The finding previously established that high ARHGAP36 activity is correlated with low activity in melanin-producing genes (lytic). This pigment has a significant impact on coloration in both cats and humans.
The Future of Genetic Research
Looking ahead, Sasaki said he is excited by the prospect of future explorations into feline genetics. He mentioned the audacity of exploring possible links between coat colors and personality traits in pet cats.
“For example, many cat owners swear by the idea that different coat colors and patterns are linked with different personalities,” – Hiroyuki Sasaki
While he said he was excited to see more research like this, he recognized some of the challenges that come with conducting genetic studies. His first reaction was, “It’s ambitious, but I’m excited to give this a shot.”