Dr. Elena Ruiz, a geneticist in Singapore, is analyzing a CRISPR-modified cell line where a target gene is edited in 1 out of every 8 cells. She starts with 2.4 million undifferentiated stem cells and applications the CRISPR guide RNA to the entire population. After editing, 25% of the edited cells undergo unintended off-target mutations and are removed from analysis. How many viable edited cells remain?

Thu, 07 May 2026 20:06:39 +0000

**Dr. Elena Ruiz, a geneticist in Singapore, is analyzing a CRISPR-modified cell line where a target gene is edited in 1 out of every 8 cells. She starts with 2.4 million undifferentiated stem cells and applies the CRISPR guide RNA across the entire population. After editing, 25% of the edited cells develop unintended off-target mutations and are removed from analysis. How many viable edited cells remain? **Why This Experiment Matters in Modern Biology**
In an era of precision medicine and gene editing breakthroughs, scientists face complex challenges in ensuring CRISPR-guided therapies deliver only intended changes. Dr. Elena Ruiz’s work highlights a critical issue: even when targeting a specific gene in a large cell population, not every edit succeeds cleanly—off-target effects remain a key hurdle. With this experiment, researchers assess the viability of edited cells under realistic constraints, shedding light on the practical efficiency of gene-editing tools in live populations. **The Numbers Behind the Edit**
Starting with 2.4 million undifferentiated stem cells, only 1 in 8 undergoes the intended gene edit, meaning approximately 300,000 cells are successfully modified. This baseline reflects the precision currently achievable in CRISPR applications, where each cell is exposed to guide RNA with room for variability. After editing, 25% of these edited cells develop unintended off-target mutations—changes unrelated to the intended gene—and are removed to maintain data integrity. This loss rate signals the reliability risks inherent in large-scale genetic experiments.