Original title: Somatic Mosaic AXIN2-associated Colonic Polyposis Predominantly Involving the Proximal Colon: A Case Report
Takashi Murakami, Masami Arai, Hidetaka Eguchi, Yuka Hirasawa +6 · August 2026
Most patients who grow large numbers of precancerous colon growths, called polyps, inherit a broken gene from their parents. However, some people get polyps without these known inherited changes. In this report, doctors examined a 77-year-old asymptomatic man who had multiple polyps mostly clustered in the proximal colon, which is the start of the large intestine. Doctors treated him by repeatedly cutting out these growths using camera-guided procedures called endoscopies. To find the cause, they tested his DNA. Usually, inherited DNA mistakes appear in blood tests. His blood and normal colon tissue showed no gene errors. Instead, the exact same mutation in a gene called AXIN2A gene that helps control cell growth and division. was found only inside his polyps. This showed he had somatic mosaicism, meaning the genetic mistake happened in a single cell during development and spread only to part of his body. This case reveals a new way this rare condition can develop.
Imagine a gardener notices that some plants in one corner of the garden are growing wildly out of control. He checks the soil in the whole garden and finds it normal. But when he tests the soil right around those plants, he discovers a hidden fertilizer spill that only affects that spot. In this paper, the patient's colon polyps had a genetic mutation that was not found in his blood or normal tissue, only in the polyp cells themselves.
For patients with multiple colon polyps but no known genetic cause, this case shows that the mutation may be hiding in the polyps themselves, not in the blood. That changes how doctors test and treat them. It also suggests that aggressive endoscopic removal and close monitoring can work, avoiding more drastic surgery.
This is a single case report, so the findings may not apply to all patients. The long-term effectiveness of intensive endoscopic management is not proven. The exact frequency of somatic mosaicism in AXIN2-associated polyposis remains unknown.
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Somatic Mosaic AXIN2-associated Colonic Polyposis Predominantly Involving the Proximal Colon: A Case Report — Takashi Murakami, Masami Arai, Hidetaka Eguchi et al. — DEN open — doi:10.1002/deo2.70409
Abstract licence: CC BY
Explanation generated by Synthesis from the abstract — it is not the original paper.