Redefining Normal: Study Shows Mutations Even in Healthy Tissues Throughout the Body

June 6, 2019

(STAT News) – A large-scale analysis published Thursday in Science examined more than 6,700 samples of normal human tissue from 29 major tissue groups — from brain and bladder to breast and prostate tissue. The researchers used RNA sequencing data to look in these tissues for large mutational clones — groups of cells that have the same mutations. They found many more clones than they had expected, including some that contained mutations that drive cancer. “This study opens up the big question of what is normal?” said Cristian Tomasetti, an associate professor of oncology at Johns Hopkins University who was not involved with the study. “This is now a picture of our normal tissues being quite messy and full of these mutational clones. We are really at the beginning of knowing how to evaluate them.”

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