Yue Fagui, Jiang Yuting, Yu Yang, Yang Xiao, Zhang Hongguo, Liu Ruizhi, Wang Ruixue
Center for Reproductive Medicine and Center for Prenatal Diagnosis, First Hospital.
Jilin Engineering Research Center for Reproductive Medicine and Genetics, Jilin University, Changchun, China.
Medicine (Baltimore). 2018 Nov;97(45):e13094. doi: 10.1097/MD.0000000000013094.
Chromosome deletion/duplication has been reported to be associated with mental disability and dysmorphism according to the accumulated research evidence.
A 25-year-old woman underwent amniocentesis for cytogenetic and single-nucleotide polymorphism (SNP) array analysis at 18 weeks of gestation due to the increased Down syndrome risk of 1/13.
The fetal chromosomal analysis revealed a seemingly "normal" chromosomal karyotype, but the SNP array results showed a partial duplication of chromosome 4q34.1q35.2 and a deletion of chromosome 7q34q36.3fluorescence in situ hybridization (FISH) analysis showed that the couple had normal chromosome 4 and 7, whereas there was a partial signal fragment of chromosome 4 attached on the long arm of chromosome 7 for the fetus.
The couple finally chose to terminate the pregnancy based on the ultrasonic multiple malformations and the abnormal SNP array results.
The duplicated/deleted segments of the fetus were de novo. Meanwhile, we consider SHH and XRCC2 as good candidate genes, which may, in part, explain the observed abnormalities for the fetus.
The combination of SNP array and FISH analysis can give a molecular chromosomal diagnosis, which will offer more clear cytogenetic diagnosis and genetic counseling.
根据累积的研究证据,染色体缺失/重复已被报道与智力残疾和畸形有关。
一名25岁女性因唐氏综合征风险增加至1/13,在妊娠18周时接受了羊水穿刺术以进行细胞遗传学和单核苷酸多态性(SNP)阵列分析。
胎儿染色体分析显示看似“正常”的染色体核型,但SNP阵列结果显示4号染色体q34.1q35.2部分重复,7号染色体q34q36.3缺失。荧光原位杂交(FISH)分析显示这对夫妇的4号和7号染色体正常,而胎儿的7号染色体长臂上附着有4号染色体的部分信号片段。
基于超声检查发现的多种畸形以及SNP阵列结果异常,这对夫妇最终选择终止妊娠。
胎儿的重复/缺失片段为新发突变。同时,我们认为SHH和XRCC2是很好的候选基因,它们可能部分解释了观察到的胎儿异常情况。
SNP阵列和FISH分析相结合可进行分子染色体诊断,这将提供更清晰的细胞遗传学诊断和遗传咨询。