骨髓增生异常肿瘤（MDS）是克隆性造血肿瘤。在40-45％的从头MDS和高达80％的细胞毒性治疗后MDS（MDS-pCT）中检测到染色体异常（CA）。最近,世界卫生组织(WHO)分类和国际共识分类(ICC)出现了一些变化.新型“双等位基因TP53失活”（也称为“多命中TP53”）MDS实体需要对TP53基因座进行系统研究（17p13.1）。ICC保持CA，允许诊断无发育不良的MDS(del(5q)，del(7q),-7和复杂核型）。删除5q是唯一的CA，仍然代表着自己的低爆炸等级，如果孤立或与除-7或del（7q）以外的一个额外CA相关，并且没有多次命中TP53。它代表了成人MDS中最常见的畸变之一，7号染色体畸变,三体8.相反，易位在MDS中是罕见的。在儿童中，del（5q）非常罕见，而-7和del（7q）占优势。种系易感性的鉴定是儿童MDS的关键。染色体5、7和17的畸变在MDS-pCT中最常见，以复杂核型分组。尽管分子特征越来越重要,细胞遗传学仍然是诊断和预后的主要部分。2022年，提出了分子国际预后评分(IPSS-M)，将突变基因的预后价值与包括细胞遗传学在内的先前评分参数（IPSS-R）相结合，仍然是必不可少的。骨髓核型在MDS的诊断中仍然是强制性的，现在需要补充分子分析。使用FISH或提供类似信息的其他技术进行分析可能是必要的，以便在核型失败的情况下完成和帮助。对于可疑的CA，为了进行克隆性评估，并用于检测TP53缺失以评估TP53双等位基因改变。
Myelodysplastic neoplasms (MDS) are clonal hematopoietic neoplasms. Chromosomal abnormalities (CAs) are detected in 40-45% of de novo MDS and up to 80% of post-cytotoxic therapy MDS (MDS-pCT). Lately, several changes appeared in World Health Organization (WHO) classification and International
Consensus Classification (ICC). The novel \'biallelic TP53 inactivation\' (also called \'multi-hit TP53\') MDS entity requires systematic investigation of TP53 locus (17p13.1). The ICC maintains CA allowing the diagnosis of MDS without dysplasia (del(5q), del(7q), -7 and complex karyotype). Deletion 5q is the only CA, still representing a low blast class of its own, if isolated or associated with one additional CA other than -7 or del(7q) and without multi-hit TP53. It represents one of the most frequent aberrations in adults\' MDS, with chromosome 7 aberrations, and trisomy 8. Conversely, translocations are rarer in MDS. In children, del(5q) is very rare while -7 and del(7q) are predominant. Identification of a germline predisposition is key in childhood MDS. Aberrations of chromosomes 5, 7 and 17 are the most frequent in MDS-pCT, grouped in complex karyotypes. Despite the ever-increasing importance of molecular features, cytogenetics remains a major part of diagnosis and prognosis. In 2022, a molecular international prognostic score (IPSS-M) was proposed, combining the prognostic value of mutated genes to the previous scoring parameters (IPSS-R) including cytogenetics, still essential. A karyotype on bone marrow remains mandatory at diagnosis of MDS with complementary molecular analyses now required. Analyses with FISH or other technologies providing similar information can be necessary to complete and help in case of karyotype failure, for doubtful CA, for clonality assessment, and for detection of TP53 deletion to assess TP53 biallelic alterations.
