Why are orange cats orange? A small missing piece of DNA is why, 2 new studies explain

Yahoo

17-05-2025

Orange cats may be known for their silly behavior, but two new studies are a step closer to understanding "the why" behind the furry felines' coloring.
Two independent studies published on May 15 by geneticists in Japan and from Stanford University in California explain how orange cats' coloring is a direct result of a missing DNA code near a specific protein found within the X chromosome. Inherently, the studies also explain why most orange cats, about 80%, are male.
So, to answer the question: What makes orange cats orange? Here's a deeper look into the findings of the two studies.
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Both studies found that a small missing piece of DNA code located next to the Rho GTPase-activating protein (ARHGAP36) resulted in orange fur coloration. In cats, ARHGAP36 is responsible for fur coloration.
When this piece of DNA is missing, it causes ARHGAP36 to become more abundant, roughly 10 times more abundant, Gregory Barsh, Stanford University genetics professor and study co-author, told USA TODAY. This leads to the production of more red, orange or yellow pigment, which is incorporated into a cat's hair.
This type of mutation is "very unusual," according to Barsh.
"Most mutations ... like genetic conditions in humans ... (are) inactivate or take away the function of a gene," Barsh said. "But what this does is really different. It increases the expression of this gene ARHGAP36, and moreover, it does it in a specific type of cell, the pigment cell ... that is found in hair, eye and skin color."
So why does this happen? Why does an increased amount of ARHGAP36 result in orange fur?
"It's interfering with a central signaling pathway, a hormonal signaling pathway that's present in many, many cells of the body ... basically all animals," Barsh said. "That is a hormonal signaling pathway that ... normally produces black or brown pigment. What increased expression of a ARHGAP36 does it is destroys that signaling pathway, or it inhibits that signaling pathway. So instead, the melanocytes (cells that form melanin) make red or yellow pigment."
Most orange cats are male, about 80%, to be more exact, according to the Regional Animal Protection Society. And the findings from the recent studies make sense of why.
ARHGAP36 is found within the X chromosome. Females have two X chromosomes, and males have an X chromosome and a Y chromosome. For the mutation to appear in female cats, it would need to occur in both X chromosomes, which has a lesser chance of occurring than in a male's one X chromosome.
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Learning about the ARHGAP36 mutation goes beyond just understanding cats.
The gene is found in all animals, including humans, Barsh said. Learning how it functions allows researchers to better understand hormonal signaling pathways as a general phenomenon.
As cat lovers, Barsh said he and his research team worked with volunteers and nonprofit organizations to collect the samples necessary for their study.
First, the team worked with cat owners to obtain voluntary samples. Barsh said the study's lead author, Stanford University genetics professor Christopher Kaelin, went to several cat shows and asked owners if he could swab their cats' cheeks for samples.
The team also partnered with spay and neuter clinics to study tissue samples. In some cases, when a female cat is neutered, she is already pregnant, Barsh said, adding that the fetal tissue, or the embryonic tissue, gets discarded. When partnering with clinics, Barsh and his team collected these tissue samples instead to use for their study.
While the two studies were completed independently, Barsh said the researchers have been in contact with each other for the last year and decided to publish in the same peer-reviewed journal, "Current Biology," on the same day.
Greta Cross is a national trending reporter at USA TODAY. Story idea? Email her at [e-mail].
This article originally appeared on USA TODAY: Why are orange cats orange? A missing piece of DNA explains why