Abstract：
OBJECTIVE: Kleefstra syndrome (KS), formerly known as 9q subtelomeric deletion syndrome, is characterized by multiple structural abnormalities. However, most fetuses do not have obvious abnormal phenotypes. In this study, the fetus with KS presented with multiple system structural anomalies, and we aimed to explore the genotype-phenotype correlations of KS fetuses.
METHODS: Multiple systematic structural anomalies, including severe intrauterine growth restriction (IUGR) and cardiac defects, were detected by ultrasound in the fetus at 33 + 5 weeks\' gestation. These abnormalities may be caused by the pathogenic deleted fragment at 9q34.3, including the euchromatic histone methyltransferase 1 (EHMT1) and collagen type V alpha 1 chain (COL5A1) genes, detected by copy number variation sequencing (CNV-seq).
CONCLUSIONS: It is essential for clinicians to perform CNV-seq combined with multidisciplinary consultation for suspected KS fetuses, especially those with multiple systematic structural anomalies.
METHODS: Multiple systematic structural anomalies, including severe intrauterine growth restriction (IUGR) and cardiac defects, were detected by ultrasound in the fetus at 33 + 5 weeks\' gestation. These abnormalities may be caused by the pathogenic deleted fragment at 9q34.3, including the euchromatic histone methyltransferase 1 (EHMT1) and collagen type V alpha 1 chain (COL5A1) genes, detected by copy number variation sequencing (CNV-seq).
CONCLUSIONS: It is essential for clinicians to perform CNV-seq combined with multidisciplinary consultation for suspected KS fetuses, especially those with multiple systematic structural anomalies.
摘要：
目标：Kleefstra综合征（KS），以前称为9q亚端粒缺失综合征，具有多重结构异常的特点。然而,大多数胎儿没有明显的异常表型。在这项研究中,患有KS的胎儿表现出多个系统结构异常，我们旨在探讨KS胎儿的基因型-表型相关性。
方法：多个系统结构异常，包括严重的宫内生长受限（IUGR）和心脏缺陷，在妊娠33+5周时通过超声检测到胎儿。这些异常可能是由9q34.3的致病性缺失片段引起的，包括原色组蛋白甲基转移酶1（EHMT1）和V型胶原α1链（COL5A1）基因，通过拷贝数变异测序(CNV-seq)检测。
结论：临床医生必须对疑似KS胎儿进行CNV-seq结合多学科咨询，尤其是那些有多重系统结构异常的人。
方法：多个系统结构异常，包括严重的宫内生长受限（IUGR）和心脏缺陷，在妊娠33+5周时通过超声检测到胎儿。这些异常可能是由9q34.3的致病性缺失片段引起的，包括原色组蛋白甲基转移酶1（EHMT1）和V型胶原α1链（COL5A1）基因，通过拷贝数变异测序(CNV-seq)检测。
结论：临床医生必须对疑似KS胎儿进行CNV-seq结合多学科咨询，尤其是那些有多重系统结构异常的人。
