The First Affiliated Hospital of Zhengzhou University, Genetic and Prenatal Diagnosis Center, Zhengzhou, Henan, 450052, China.
Taiwan J Obstet Gynecol. 2023 Jan;62(1):94-100. doi: 10.1016/j.tjog.2022.06.018.
To define the genotype-phenotype correlation of small supernumerary marker chromosomes (sSMCs) and conduct precise genetic counseling, we retrospectively searched and reviewed de novo sSMCs cases detected during prenatal diagnosis at The First Affiliated Hospital of Zhengzhou University.
Chromosome karyotypes of 20,314 cases of amniotic fluid from pregnant women were performed. For 16 samples with de novo sSMCs, 10 were subjected to single-nucleotide polymorphism (SNP) array or low-coverage massively parallel copy number variation sequencing (CNV-seq) analysis.
Among the 10 sSMCs cases, two sSMCs derived from chromosome 9, and three sSMCs derived from chromosomes 12, 18 and 22. The remaining 5 cases were not identified by SNP array or CNV-seq because they lacked euchromatin or had a low proportion of mosaicism. Four of them with a karyotype of 47,XN,+mar presented normal molecular cytogenetic results (seq[hg19] 46,XN), and the remaining patient with a karyotype of 46,XN,+mar presented with Turner syndrome (seq[hg19] 45,X). Five sSMCs samples were mosaics of all 16 cases.
Considering the variable origins of sSMCs, further genetic testing of sSMCs should be performed by SNP array or CNV-seq. Detailed molecular characterization would allow precise genetic counseling for prenatal diagnosis.
为了定义小型额外标记染色体 (sSMC) 的基因型-表型相关性并进行精确的遗传咨询，我们回顾性地搜索和审查了郑州大学第一附属医院在产前诊断中检测到的新发 sSMC 病例。
对 20314 例孕妇羊水的染色体核型进行了分析。对于 16 例新发 sSMC 样本，其中 10 例进行了单核苷酸多态性 (SNP) 芯片或低覆盖度大规模平行拷贝数变异测序 (CNV-seq) 分析。
在 10 例 sSMC 病例中，有 2 例 sSMC 来源于染色体 9，3 例 sSMC 来源于染色体 12、18 和 22。其余 5 例由于缺乏常染色质或嵌合体比例低，无法通过 SNP 芯片或 CNV-seq 鉴定。其中 4 例核型为 47,XN,+mar 的患者呈现正常的分子细胞遗传学结果 (seq[hg19] 46,XN)，而剩余 1 例核型为 46,XN,+mar 的患者呈现特纳综合征 (seq[hg19] 45,X)。16 例患者中有 5 例 sSMC 为嵌合体。
鉴于 sSMC 的来源多样，应通过 SNP 芯片或 CNV-seq 对 sSMC 进行进一步的遗传检测。详细的分子特征分析将允许为产前诊断提供精确的遗传咨询。
