Peutz–Jeghers syndrome (PJS) is a hereditary polyposis syndrome characterized by hamartomatous Peutz–Jeghers polyps in the gastrointestinal tract, mucocutaneous pigmentations, and increased risk for intestinal and extraintestinal cancer. In more than two-third of patients it is possible to detect pathogenic variants in the serine/threonine kinase 11 (STK11) gene, but so far is knowledge about genetic causes in the remaining part of patients limited. Reports of STK11 mosaicism are rare but may be an explanation in some patients without initial findings of pathogenic variants in STK11. We report two Danish patients with STK11 mosaicism detected in blood when using Next-Generation Sequencing. This is only the sixth and seventh patient reported in the literature, and we compare phenotypes of the reported cases. The results indicate that STK11 mosaicism is more frequent than anticipated and highlight that mosaicism should be considered in patients with clinical suspicion of PJS or patients fulfilling the diagnostic criteria.

Peutz-Jeghers 综合征 (PJS) 是一种遗传性息肉病综合征，其特征是胃肠道错构瘤性 Peutz-Jeghers 息肉、皮肤黏膜色素沉着以及肠癌和肠外癌的风险增加。在超过三分之二的患者中，可以检测到丝氨酸/苏氨酸激酶 11 ( STK11 ) 基因中的致病变异，但到目前为止，对其余部分患者的遗传原因了解有限。STK11嵌合体的报告很少见，但可能可以解释一些没有初步发现STK11致病性变异的患者。我们报告了两名患有STK11 的丹麦患者使用下一代测序时在血液中检测到嵌合现象。这只是文献中报告的第 6 位和第 7 位患者，我们比较了报告病例的表型。结果表明STK11嵌合现象比预期的更频繁，并强调应在临床怀疑 PJS 的患者或满足诊断标准的患者中考虑嵌合现象。