Yu Yang, Jiang Yuting, Hu Xiaonan, Zhang Hongguo, Liu Ruizhi, Wang Ruixue
Cytogenet Genome Res. 2019;157(4):220-226. doi: 10.1159/000499173. Epub 2019 Apr 3.
Trisomy 18p is a rarely observed chromosomal aberration. Only 31 cases have previously been described in the literature. Trisomy 18p is associated with mild to moderate phenotypic anomalies and intellectual disability. Here, we report on a pregnant woman in whom noninvasive prenatal testing indicated a high risk of fetal trisomy 18. Prenatal diagnosis and karyotyping of the parents were performed and demonstrated that both the mother and the fetus had a derivative chromosome 15 with a segment of unknown origin. Chromosomal microarray analysis and FISH revealed a 14.9-Mb duplication of 18p and detected 3 centromeres of chromosome 18. To our knowledge, this is the first study reporting trisomy 18p due to an unbalanced translocation of 18p onto chromosome 15q showing 2-generation transmission. The results suggest that trisomy 18p can be considered a euchromatic variant.
18号染色体短臂三体是一种罕见的染色体畸变。此前文献中仅描述过31例病例。18号染色体短臂三体与轻度至中度的表型异常及智力残疾有关。在此，我们报告一名孕妇，其无创产前检测显示胎儿18号染色体三体风险高。对父母进行了产前诊断和核型分析，结果表明母亲和胎儿均有一条衍生的15号染色体，其中一段来源不明。染色体微阵列分析和荧光原位杂交显示18号染色体短臂有14.9兆碱基的重复，并检测到3个18号染色体着丝粒。据我们所知，这是第一项报道因18号染色体短臂不平衡易位至15号染色体长臂而导致的18号染色体短臂三体并显示两代遗传的研究。结果表明，18号染色体短臂三体可被视为一种常染色质变异。
