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Secret of Orange Cats Finally Revealed After 60-Year Search : ScienceAlert (opens in a new tab)

sciencealert.com · 2026-10-09

Short answerEvidenceSource

Short answer

Mixed

Mixed.

One key claim is not backed by the study. 3 other points were not covered by the paper.

  • 2 supported
  • 1 not supported
  • 3 not covered

Checked against the study summary. The full text wasn't available, so some details couldn't be settled either way.

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1
2

NewsLink checks it

Mixed

One claim isn't supported by the study. Two of six check out. Three claims the study doesn't address.

  • 2 supported
  • 1 not supported
  • 3 not covered
Open claim evidence
3
Source paper

Source layer

The 2 papers the story cites

Source study separated from background citations.

The research anchor for the report.

Then inspect each claim

Evidence layer

Claim by claim

Each claim gets a verdict. Expand it to see the evidence directly below.

6 claims in this story

Showing all 6 claimsChoose a verdict to focus the list.

Claim 1 of 6Not supportedThe article says the mutation has no obvious negative consequences for health or mental wellbeing and that claims about orange cats being less bright are scientifically unsupported.View evidenceHide evidence

Why this verdict

The supplied paper profile contains no evidence about orange-cat health, mental wellbeing, intelligence, or cognition. Those claims may be discussed in the news story, but they are not supported by this abstract-level paper profile.

Claim 2 of 6Not coveredBarsh and colleagues reported that skin cells from orange cats express 13 times as much RNA from Arhgap36 as skin cells from nonorange cats.View evidenceHide evidence

As stated13 times as much RNA

Why this verdict

The paper profile supports ectopic/melanocyte-specific Arhgap36 expression in orange cats, but the abstract-level evidence does not provide the quoted quantitative magnitude of 13-fold higher Arhgap36 RNA expression in skin cells.

1

Study evidence

A 5-kb deletion causes ectopic, melanocyte-specific expression of Arhgap36 in domestic cat skin.

“...leads to ectopic and melanocyte-specific expression of ... Arhgap36”
Claim 3 of 6Not coveredThe researchers found a 5 kilobase deletion present in every orange cat they examined in a database of 188 cats, including 145 orange cats, 6 calico/tortoiseshell cats, and 37 nonorange cats.View evidenceHide evidence

As stated5 kilobase deletion; 188 cats total

Why this verdict

The profile supports a 5-kb deletion associated with/claimed causal for Sex-linked orange, but the abstract-level profile explicitly lacks sample sizes and cohort details. It therefore cannot verify the database size of 188 cats, the subgroup counts, or the statement that the deletion was present in every orange cat examined.

1

Study evidence

Sex-linked orange is caused by a 5-kb deletion on the X chromosome.

“We show that Sex-linked orange is caused by a 5-kb deletion”
Claim 4 of 6Not coveredThe second study, led by Hidehiro Toh at Kyushu University, also identified Arhgap36 as the orange cat fur gene and said higher expression of it suppresses dark eumelanin and shifts pigment toward reddish-yellow pheomelanin.View evidenceHide evidence

Why this verdict

The profile supports that Arhgap36 is implicated in Sex-linked orange and that ectopic Arhgap36 expression leads to reduced melanogenic gene expression through downstream effects on the Mc1r-cAMP-PKA pathway. However, the abstract-level profile does not verify the separate Toh/Kyushu study attribution, and it does not specifically state the eumelanin-to-pheomelanin wording used in the story.

1

Study evidence

Sex-linked orange is caused by a 5-kb deletion on the X chromosome.

“We show that Sex-linked orange is caused by a 5-kb deletion”
2

Study evidence

A 5-kb deletion causes ectopic, melanocyte-specific expression of Arhgap36 in domestic cat skin.

“...leads to ectopic and melanocyte-specific expression of ... Arhgap36”
Claim 5 of 6SupportedTwo independent teams of researchers found that orange cat fur is likely caused by a missing segment of DNA in a non-protein-coding part of the cat genome.View evidenceHide evidence

Why this verdict

The abstract-level profile supports the core scientific claim: Sex-linked orange is reported to be caused by a 5-kb deletion on the X chromosome that leads to ectopic, melanocyte-specific Arhgap36 expression, consistent with a regulatory/non-protein-coding mechanism. The profile itself does not verify the story's contextual statement that two independent teams made the finding.

1

Study evidence

Sex-linked orange is caused by a 5-kb deletion on the X chromosome.

“We show that Sex-linked orange is caused by a 5-kb deletion”
2

Study evidence

A 5-kb deletion causes ectopic, melanocyte-specific expression of Arhgap36 in domestic cat skin.

“...leads to ectopic and melanocyte-specific expression of ... Arhgap36”
Claim 6 of 6SupportedThe story says the mutated gene is on the cat X chromosome, which explains why orange color appears differently between males and females.View evidenceHide evidence

Why this verdict

The profile states that the 5-kb deletion is on the X chromosome and concerns Sex-linked orange, and it notes the classic X-inactivation basis of tortoiseshell/calico variegation. This supports the story's explanation that X-linkage accounts for sex-dependent orange coat patterns, though 'mutated gene' is a simplification because the profile describes a deletion at/near the Arhgap36 locus rather than a protein-coding mutation in Arhgap36.

1

Study evidence

Sex-linked orange is caused by a 5-kb deletion on the X chromosome.

“We show that Sex-linked orange is caused by a 5-kb deletion”
Then look for missing context

Context layer

What the story left out

Important study details the story did not include.

  • The paper reports that Mc1r and its ability to stimulate cAMP accumulation remain intact, placing Sex-linked orange downstream of Mc1r.

    The story's presented claims do not mention intact Mc1r/cAMP signaling or the downstream-of-Mc1r epistasis conclusion.

    From ex_vivo_animal receptor stimulation and cAMP accumulation assay; ex vivo animal

  • The paper's biochemical mechanism is that Arhgap36 expression in melanocytes reduces PKA catalytic subunit levels, providing in vivo evidence that Arhgap36 can inhibit PKA.

    The story mentions pigment suppression/shift but not the PKA catalytic subunit result, which is a primary mechanistic contribution in the paper profile.

    From ex vivo animal

  • The profile notes a comparative-genomics point: no apparent homologous Sex-linked orange locus is reported in other mammals.

    This species-specificity/comparative element appears in the paper profile but is not reflected in the presented story claims or caveats.

    From secondary_data: genetic mapping and structural variant identification

3 things the story did carry across
  • The paper's central finding is that Sex-linked orange in domestic cats is caused by a 5-kb deletion on the X chromosome that drives ectopic, melanocyte-specific Arhgap36 expression.
  • The paper connects the X-linked lesion to sex-linked coat-color patterns and X-inactivation-dependent variegation in female tortoiseshell/calico cats.
  • Single-cell RNA-seq of fetal cat skin showed reduced expression of melanogenic genes normally activated by the Mc1r-cAMP-PKA pathway in red/yellow hair contexts.
Then read the study layer

Study layer

Study at a glance

Scan the study first. Expand only the parts you want to inspect.

Pieces of work

5

Evidence read

study summary

Lead result

secondary data

1Lead resultsecondary dataIdentify the causal genetic lesion underlying Sex-linked orange coat color in domestic cats and show it drives melanocyte-specific ectopic expression of Arhgap36.secondary data: genetic mapping and structural variant identificationExpand

In plain English

Genetic mapping and variant discovery identify a 5-kb deletion on the X chromosome as the causal lesion for Sex-linked orange in domestic cats; the deletion is reported to drive ectopic, melanocyte-specific expression of Arhgap36, implicating a regulatory mechanism at the Arhgap36 locus in the orange coat phenotype.

Key findings

  • Sex-linked orange is caused by a 5-kb deletion on the X chromosome.
  • The 5-kb deletion leads to ectopic, melanocyte-specific expression of Arhgap36 (Rho GTPase Activating Protein 36).
“We show that Sex-linked orange is caused by a 5-kb deletion”
What this piece can’t prove
  • Details about the population distribution/frequency of the deletion and how broadly the genotype–phenotype association was tested are not provided.

2 further details could not be confirmed from the summary.

2ex vivo animalIdentify the causal genetic lesion underlying Sex-linked orange coat color in domestic cats and show it drives melanocyte-specific ectopic expression of Arhgap36.expression localization assays (unspecified)Expand

In plain English

The paper reports that the Sex-linked orange phenotype is caused by a 5-kb deletion that leads to ectopic, melanocyte-specific expression of Arhgap36 in domestic cat skin; the abstract states this ectopic expression is linked to the deletion.

Key findings

  • A 5-kb deletion causes ectopic, melanocyte-specific expression of Arhgap36 in domestic cat skin.
“...leads to ectopic and melanocyte-specific expression of ... Arhgap36”
What this piece can’t prove
  • Ambiguity whether melanocyte-specific expression was shown via independent localization experiments (e.g., in situ or immunostaining) versus derived from scRNA-seq data; the abstract does not resolve this.

2 further details could not be confirmed from the summary.

3ex vivo animalDefine the cellular/molecular transcriptomic consequences of Sex-linked orange in fetal cat skin at single-cell resolution, linking red/yellow hair color to altered expression of melanogenic genes downstream of Mc1r signaling.single-cell RNA-seq (fetal cat skin)Expand

In plain English

Single-cell RNA-seq of fetal cat skin identifies a melanocyte transcriptional program in Sex-linked orange animals characterized by reduced expression of melanogenic genes that are normally activated by the Mc1r–cAMP–PKA pathway; Mc1r expression and its ability to stimulate cAMP accumulation are reported as intact.

Key findings

  • Red/yellow hair color in Sex-linked orange fetal cat skin is associated with reduced expression of melanogenic genes in melanocytes, as revealed by single-cell RNA-seq.
  • The down-regulated melanogenic genes are characterized as normally activated by Mc1r–cAMP–PKA signaling, while Mc1r expression and its ability to stimulate cAMP accumulation are reported as intact.
“Single-cell RNA sequencing (RNA-seq) studies from fetal cat skin reveal that red/yellow hair color is caused by reduced expression of melanogenic genes that are normally activated by the melanocortin 1 receptor (Mc1r)-cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA) pathway”
4ex vivo animalEstablish the biochemical/functional mechanism: Arhgap36 expression in melanocytes reduces PKA catalytic subunit levels; Mc1r-cAMP responsiveness remains intact; therefore Sex-linked orange acts downstream of Mc1r.ex vivo animal receptor stimulation and cAMP accumulation assayExpand

In plain English

The abstract reports that Mc1r and its ability to stimulate cAMP accumulation are intact in the Sex-linked orange context, based on comparative signaling readouts; this supports the conclusion that Sex-linked orange acts genetically and biochemically downstream of Mc1r.

Key findings

  • Mc1r and its ability to stimulate cAMP accumulation are intact in Sex-linked orange; therefore the mutation functions downstream of Mc1r.
“...but Mc1r and its ability to stimulate cAMP accumulation is intact.”
What this piece can’t prove

3 further details could not be confirmed from the summary.

5ex vivo animalEstablish the biochemical/functional mechanism: Arhgap36 expression in melanocytes reduces PKA catalytic subunit levels; Mc1r-cAMP responsiveness remains intact; therefore Sex-linked orange acts downstream of Mc1r.Expand

In plain English

From paper abstract: ectopic, melanocyte-specific expression of Arhgap36 reduces levels of the PKA catalytic subunit (PKA_C); Mc1r signaling (cAMP generation in response to Mc1r) remains intact, placing Sex-linked orange genetically and biochemically downstream of Mc1r via suppression of PKA activity.

Key findings

  • Arhgap36 expression in melanocytes leads to reduced levels of the PKA catalytic subunit (PKA_C).
  • Mc1r signaling (ability to stimulate cAMP accumulation) is intact, indicating the orange phenotype is not due to impaired Mc1r/cAMP generation.
“Instead, we show that expression of Arhgap36 in melanocytes leads to reduced levels of the PKA catalytic subunit (PKA_C); thus, Sex-linked orange is genetically and biochemically downstream of Mc1r.”
What this piece can’t prove
  • Abstract does not specify the exact assays used to measure PKA_C or cAMP, preventing assessment of assay sensitivity, cellular resolution, or potential confounders.

2 further details could not be confirmed from the summary.

Finally, the search trail

Method layer

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Papers considered

The selected paper, plus nearby candidates.

Europe PMC, Crossref, PubMed · 15 candidate papers

And 9 more candidates considered.