Lynch syndrome (LS) is an autosomal dominant cancer predisposition syndrome defined molecularly by the presence of a pathogenic heterozygous variant in one of the mismatch repair genes: MLH1, MSH2, MSH6, PMS2, or EPCAM. The incidence of LS in the general population is estimated at 1 in 279, with an even higher incidence in those with colorectal cancer and endometrial cancer, the two most common Lynch-associated cancers. Lynch syndrome is currently considered an “adult onset” cancer predisposition syndrome, with the majority of malignancies appearing in adulthood, and recommended screening beginning in adulthood. At present, expert guidelines discourage testing minors for Lynch syndrome.

We report seven cases in which children presented with LS and pediatric malignancy, suggesting possible association of childhood onset of cancers with monoallelic mismatch repair deficiency.

Lynch 综合征 (LS) 是一种常染色体显性遗传癌症易感综合征，其分子定义是在以下错配修复基因中存在致病性杂合变异：  MLH1、MSH2、MSH6、PMS2或 EPCAM。一般人群中 LS 的发病率估计为 279 分之一，结直肠癌和子宫内膜癌这两种最常见的 Lynch 相关癌症的发病率更高。Lynch 综合征目前被认为是一种“成人发病”癌症易感综合征，大多数恶性肿瘤出现在成年期，建议从成年期开始筛查。目前，专家指南不鼓励对未成年人进行林奇综合征检测。

我们报告了 7 例儿童患有 LS 和小儿恶性肿瘤的病例，这表明儿童癌症的发病可能与单等位基因错配修复缺陷有关。