"Radical transgender experiments": Nancy Mace's "TRANS MICE Act" goes to war with the transgenic lab mice scientists use to study cancer

On June 18, 2026, Nancy Mace went to X to promote a piece of legislation with her name on it. She posted:

"Animals should not be used for radical transgender experiments.

This is not science. This is ideological cruelty paid for by the American taxpayers.

Our TRANS MICE Act ends it. No federal funds may be used to conduct, support, or fund research aimed at altering an animal's..."

Mace's post on X (@RepNancyMace, June 18, 2026), promoting H.R.4512, the "TRANS MICE Act." The animal in the photo she chose is a standard white laboratory mouse.

The mice are transgenic, not transgender

The bill is real. H.R.4512, introduced by Mace on August 1, 2025, carries the official long title "Transgender Research on Animals Now Stops and Money for Ideological Cruelty Eliminated Act", which spells out, letter by letter, to TRANS MICE.

The research it targets is also real, and it is not what the bill's name says it is. The federally funded animal studies in question use transgenic mice: rodents that have had foreign DNA inserted into their genome so that scientists can watch how specific genes drive disease. They are one of the most common tools in modern biomedical research. The U.S. National Cancer Institute and other agencies fund them to study cancer, endometriosis, infertility, breast cancer and prostate cancer, among other conditions.

"Transgenic" and "transgender" are not the same word, and they are not the same thing. One is a 40-year-old term of genetic engineering; the other describes human gender identity. The mice are genetically modified. They are not transgender.

Americans for Medical Progress, a research-advocacy group, addressed the mix-up directly: the studies are "not related to gender identity," it said, but are "focused on studying biological and reproductive development," and the animals "are not 'transgender' in any human or social context." The point of the work, the group said, is to understand "how sex hormones function and their effect when things go wrong," which is what gives doctors a shot at helping patients facing infertility or a cancer diagnosis.

What the bill actually does

H.R.4512 would bar federal money from any research that "seeks to alter an animal's biological sex" through drugs, hormones, surgery or other interventions, with a carve-out for species that naturally change sex on their own. The operative effect, as written, would sweep across the transgenic-animal research that scientists say has nothing to do with gender at all.

"This is not science. This is ideological cruelty paid for by the American taxpayers. Our TRANS MICE Act ends it."

Nancy Mace, June 18, 2026

How it landed

The post was covered as a self-own. The Poke called it "a mortifying self-own for the ages," and the replies under Mace's own post made the same correction over and over. "This soon to be former member of Congress does not understand that the studies refer to TRANSGENIC mice," read one. Others pointed out that the very photo Mace attached, a white mouse being handled in a lab, is the standard image of a transgenic research animal.

X added a community note to the post correcting the premise:

"'Trans mice' refers to transgenic mice not transgender mice. Transgenic mice are defined as mice that have incorporated foreign DNA into their genome, allowing for the study of gene function and disease mechanisms, particularly in cancer research."

Community note appended to Mace's June 18, 2026 post

Mace did not back off. She clapped back at the note, arguing the bill was never about transgenic mice in the first place:

"This post is not about transgenic mice. It is about federally funded transgender-related experiments on animals. The bill is called the Transgender Research on Animals Now Stops and Money for Ideological Cruelty Eliminated Act, also known as the TRANS MICE Act. The Community Note addresses 'transgenic mice,' which is a completely different topic."

Nancy Mace, replying to the community note, June 18, 2026

The replies: "one of the funniest things I've seen a real life politician post"

The Irish Star, in a roundup headlined "Nancy Mace branded 'dumbest member of Congress' as she's eviscerated over 'trans mice' claim" (Jeremiah Hassel, June 20, 2026), collected a sampling of the replies and quote-posts. The mix was part correction, part comedy:

"It's depressingly funny that these people don't understand the word transgenic. Transgenic research is how we now have mass produced insulin. Nobody is making trans'gender' mice. Wtf"

One X user, as collected by the Irish Star

"As someone who works with transgenic mouse models for cancer research, this is objectively one of the funniest things I've seen a real life politician post."

A cancer researcher replying to Mace, as collected by the Irish Star

"Apparently this is not an April Fools joke. This person really doesn't know that trans mice are transgenic and not transgender."

Another reply, as collected by the Irish Star

"Translation: Not transgender. Transmission: Not transgender. Transportation: Not transgender. Transatlantic: Not transgender. Transgenic: Also not transgender. English is hard."

A reply listing five "trans" words that have nothing to do with gender, as collected by the Irish Star

One commenter, the Irish Star reported, "went so far as to call Mace 'the dumbest member of Congress.'" That "dumbest member" and "bozo" framing belongs to the commenters and the outlets that quoted them, not to any settled fact; what is verifiable is that the studies the bill targets are transgenic-animal research, which the cited scientific sources say has nothing to do with gender identity.

The Irish Star also noted that the error is not new to Mace: President Donald Trump made the same "making mice transgender" claim the year before, likewise referring to medical research that had nothing to do with gender-affirming care.

Mace's office has defended the bill by pointing to what it characterizes as roughly $10 million in taxpayer spending on "transgender animals." Scientists and Americans for Medical Progress dispute the framing, saying the underlying studies are transgenic-animal research that the bill's name misreads. The terminology is the whole argument: the legislation is built on a word that is one consonant away from the one it means, and a field of biology in between.

Sources & related coverage

• The post itself: Mace on X (@RepNancyMace), June 18, 2026
• The bill: H.R.4512, the "TRANS MICE Act," 119th Congress
• The "self-own" coverage: The Poke, June 20, 2026
• The replies roundup: Irish Star, "Nancy Mace branded 'dumbest member of Congress' as she's eviscerated over 'trans mice' claim," Jeremiah Hassel, June 20, 2026
• The scientific correction: The Advocate, "Nancy Mace goes after nonexistent 'trans mice' research" (Aug 20, 2025); Americans for Medical Progress
• What transgenic mice are: U.S. National Cancer Institute
• Mace's own framing: Rep. Nancy Mace, "Introduces Bill to End Taxpayer Funded Radical Animal Experiments"

This dispatch catalogs Nancy Mace's own dated, public posts and on-record legislation, alongside the published scientific record and named third-party commentary. Characterizations of the post are attributed to their speakers; the descriptions of transgenic-mouse research reflect the cited scientific sources.