Background Pallister-Killian syndrome (PKS) (OMIM:#601803) is a rare sporadic genetic disorder characterized by multi-malformations which is caused by the presence of the extra isochromosome 12p. PKS is featured by the tissue-limited mosaicism of the isochromosome 12p [i(12p)]. There were a wide spectrum of prenatal ultrasound findings of PKS, which made it difficult to be found in first or second trimester. Polyhydramnios, diaphragmatic hernia, and rhizomelic limb shortening were the most common prenatal ultrasound abnormalities in PKS. This study retrospectively analyzed the ultrasound findings and molecular cytogenetic results of four PKS fetuses diagnosed by using cord blood samples. Results The ultrasound anomalies of four PKS fetuses are described as follows: fetal macrosomia, cerebral ventriculomegaly, increased NT thickness, rhizomelic limbs shortening, polyhydramnios. Biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), femur length (FL) measurements were above the mean in three fetuses,while one fetus showed rhizomelic limbs shortening. Combined with this study and previous literature, polyhydramnios was the most frequent anomaly observed in prenatal ultrasound examination of PKS, which accounted for 48% (94/194). Fetal macrosomia was present in 15% (29/194), cerebral ventriculomegaly in 13% (25/194), thickened nuchal fold in 9% (18/194), rhizomelic limbs shortening in 26% (51/194). I(12p) was found in the karyotype analysis of cultured cord blood lymphocytes and the mosaic ratios ranged from 2 to 5%. Single nucleotide polymorphisms array (SNP-array) results suggested that the whole short arm of chromosome 12 was duplicated with 2~3 copies. Fluorescence in situ hybridization (FISH) was performed to confirm the results of karyotype and SNP-array. Conclusions In case non-specific indicators such as fetal macrosomia, polyhydramnios and rhizomelic limbs shortening are observed meanwhile in prenatal ultrasound, targeted detection of PKS should be considered. In the prenatal diagnosis of PKS, the combination of SNP-array and FISH with conventional karyotype are the key to seek i(12p) and for precise diagnosis.

中文翻译：

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使用脐带血样本进行 Pallister-Killian 综合征的产前诊断。

背景 Pallister-Killian 综合征 (PKS) (OMIM:#601803) 是一种罕见的散发性遗传疾病，其特征是由额外的等染色体 12p 的存在引起的多发性畸形。PKS 的特点是等染色体 12p [i(12p)] 的组织受限嵌合。PKS的产前超声发现范围很广，这使得在妊娠早期或中期很难被发现。羊水过多、膈疝和根状肢缩短是 PKS 中最常见的产前超声异常。本研究回顾性分析了使用脐带血样本诊断的 4 例 PKS 胎儿的超声检查结果和分子细胞遗传学结果。结果 4例PKS胎儿的超声异常描述如下：巨大儿、脑室扩大、NT增厚、根茎四肢缩短，羊水过多。三个胎儿的双顶径(BPD)、头围(HC)、腹围(AC)、股骨长度(FL)测量值高于平均值，而一个胎儿显示出根状肢缩短。结合本研究及以往文献，羊水过多是PKS产前超声检查中最常见的异常，占48%（94/194）。15% (29/194) 出现巨大胎儿，13% (25/194) 出现脑室扩大，9% (18/194) 出现颈褶增厚，26% (51/194) 出现根状肢缩短。在培养的脐血淋巴细胞的核型分析中发现了I(12p)，嵌合率在2%到5%之间。单核苷酸多态性阵列（SNP-array）结果表明，12号染色体的整个短臂重复了2~3个拷贝。进行荧光原位杂交 (FISH) 以确认核型和 SNP 阵列的结果。结论 产前超声同时观察到巨大胎儿、羊水过多、根状肢缩短等非特异性指标时，应考虑针对性检测PKS。在PKS产前诊断中，SNP-array和FISH结合常规核型是寻找i(12p)和精准诊断的关键。产前超声同时观察到羊水过多和根状肢缩短，应考虑针对性检测PKS。在PKS产前诊断中，SNP-array和FISH结合常规核型是寻找i(12p)和精准诊断的关键。产前超声同时观察到羊水过多和根状肢缩短，应考虑针对性检测PKS。在PKS产前诊断中，SNP-array和FISH结合常规核型是寻找i(12p)和精准诊断的关键。