微卫星不稳定性（MSI）是一种由脱氧核糖核酸（DNA）错配修复系统缺陷引起的现象，是癌症研究和临床诊断中的重要生物标志物。 MSI 检测通常涉及下一代测序数据，许多研究都集中在 DNA 上。在这里，我们介绍了一种新方法，通过直接从核糖核酸测序 (RNA-seq) 数据测量微卫星长度并比较其分布来检测 MSI。我们的研究结果揭示了 MSI 高 (MSI-H) 和微卫星稳定样本之间明显的不稳定模式，表明基于 RNA 的 MSI 检测的有效性。此外，3'-非翻译区域的微卫星对 MSI 检测显示出最大的预测价值。值得注意的是，这种功效延伸到检测 MSI-H 样本，甚至在通常与 MSI 不相关的肿瘤中也是如此。我们的方法强调了 RNA-seq 数据在 MSI 检测中的实用性，通过整合各种生物数据促进更精确的诊断。© 作者 2024。由牛津大学出版社出版。

Microsatellite instability (MSI), a phenomenon caused by deoxyribonucleic acid (DNA) mismatch repair system deficiencies, is an important biomarker in cancer research and clinical diagnostics. MSI detection often involves next-generation sequencing data, with many studies focusing on DNA. Here, we introduce a novel approach by measuring microsatellite lengths directly from ribonucleic acid sequencing (RNA-seq) data and comparing its distribution to detect MSI. Our findings reveal distinct instability patterns between MSI-high (MSI-H) and microsatellite stable samples, indicating the efficacy of RNA-based MSI detection. Additionally, microsatellites in the 3'-untranslated regions showed the greatest predictive value for MSI detection. Notably, this efficacy extends to detecting MSI-H samples even in tumors not commonly associated with MSI. Our approach highlights the utility of RNA-seq data in MSI detection, facilitating more precise diagnostics through the integration of various biological data.© The Author(s) 2024. Published by Oxford University Press.