Gastrenterology, Hospital de Castelo Branco, Portugal.
Gastroenterology, Portuguese Oncology Institute of Porto, Portugal.
Rev Esp Enferm Dig. 2022 Dec;114(12):750-751. doi: 10.17235/reed.2022.8928/2022.
Biallelic mismatch repair deficiency (BMMRD) is a rare autosomal recessive disorder characterized by numerous early-onset cancers, especially gastrointestinal tumors. Biallelic germline mutations in one of four mismatch repair (MMR) genes (MLH1, MSH2, MSH6, or PMS2) cause this devastating disease. Given the rarity of the syndrome, often-asymptomatic tumors, diagnosis is frequently unrecognized or delayed. A high degree of clinical awareness is needed to identify new cases. Immunohistochemical assessment of MMR protein expression and analysis of microsatellite instability are the first tools with which to initiate the study of this syndrome in solid malignancies. MMR immunohistochemical shows a hallmark pattern with absence of staining in both neoplastic and non-neoplastic cells for the biallelic mutated gene. We present a unique case of a young boy diagnosed with invasive colon adenocarcinoma and brain tumor, with classical BMMRD features, found to have biallelic pathogenic PMS2 mutations.
双等位基因错配修复缺陷 (BMMRD) 是一种罕见的常染色体隐性疾病，其特征是多种早发性癌症，特别是胃肠道肿瘤。四个错配修复 (MMR) 基因（MLH1、MSH2、MSH6 或 PMS2）之一的双等位基因突变会导致这种毁灭性疾病。鉴于该综合征极为罕见，且常无症状的肿瘤，因此诊断通常未被识别或被延迟。需要高度的临床意识才能发现新病例。对 MMR 蛋白表达的免疫组织化学评估和微卫星不稳定性分析是启动对实体恶性肿瘤中该综合征研究的最初工具。MMR 免疫组织化学显示出一种特征性模式，即双等位基因突变的肿瘤细胞和非肿瘤细胞均无染色。我们介绍了一个独特的年轻男孩病例，他被诊断患有浸润性结肠腺癌和脑肿瘤，具有典型的 BMMRD 特征，发现存在双等位基因致病性 PMS2 突变。
