What's already known about this topic? (1) Sequencing-based noninvasive testing can detect large copy number abnormalities and some autosomal dominant single-gene disorders; (2) Exome sequencing (ES) on fetal samples provides 20% diagnostic yield for structural abnormalities after normal karyotype & microarray. What does this study add? (1) ES on cell-free DNA in three gravid patients with suspected genetic disease in the fetus; (2) We demonstrate broad sequencing approaches are limited by sampling and technical difficulties, concluding broad sequencing is currently inappropriate for noninvasive testing.

中文翻译：

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无创产前外显子组测序效率低，无法检测单基因疾病-问题和可能的解决方案

关于此主题的已知信息是什么？（1）基于测序的无创检测可以检测大量拷贝数异常和一些常染色体显性单基因疾病；（2）胎儿样品上的外显子组测序（ES）可为正常核型和微阵列检测出20％的结构异常诊断率。这项研究增加了什么？（1）在三名怀疑患有胎儿遗传病的妊娠患者中，用无细胞DNA进行ES检测；（2）我们证明了广泛的测序方法受到抽样和技术难题的限制，因此得出结论，目前广泛的测序尚不适用于无创检测。