在法医遗传学中，有时，生前采集的福尔马林固定石蜡包埋 (FFPE) 活检材料是唯一可用于个人身份识别或亲子鉴定的生物样本。在大多数情况下，这种生物组织的特点是存在肿瘤细胞，其特征是与正常组织细胞中存在的 DNA 相比不稳定和微卫星 (MSI/LOH) 杂合性丧失。在本病例报告中，来自同一男性受试者可用于基因研究：一份样本具有结直肠癌组织，另一份样本具有正常组织（无癌组织病理学特征）。从两种组织中提取的 DNA 获得的遗传图谱的比较表明，在肿瘤组织中存在影响位于三个不同常染色体上的 FGA、CSF1P0、D21S2055 基因座的三种基因组不稳定现象，以及影响 DYS438 的一种重复现象。因此，由于MSI/LOH现象，从肿瘤组织获得的基因图谱被扭曲，从而产生了一个虚构的基因图谱，与受试者的真实基因图谱（不含肿瘤细胞的正常组织）不符。© 2024。作者（ s）。

In forensic genetics, sometimes formalin-fixed paraffin-embedded (FFPE) biopsy material taken during life is the only biological sample available for individual identification or paternity testing. In most cases, this biological tissue is characterized by the presence of tumor cells characterized by instability and loss of heterozygosity of microsatellites (MSI/LOH) compared to the DNA present in cells of normal tissue.In this case report, two FFPE samples from the same male subject were available for genetic investigation: one sample with colorectal cancer tissue and the other with normal tissue (no cancerous histopathological features). The comparison of the genetic profiles obtained from DNA extracted from the two tissues showed in the tumor tissue the presence of three genomic instability phenomena affecting FGA, CSF1P0, D21S2055 loci, located on three distinct autosomal chromosomes, and one duplication phenomenon affecting the DYS438. Therefore, due to the MSI/LOH phenomena, the genetic profile acquired from the tumor tissue was distorted and thus generated a fictitious genetic profile, not corresponding to the subject's real one (normal tissue free of tumor cells).© 2024. The Author(s).