PNAS：对人类胚胎遗传缺陷的整合筛查

近日，在PNAS上科研人员报告了一种具有成本效益的基于下一代dna测序的整合方法，用于在胚胎着床前遗传诊断和筛查期间筛查人类胚胎的遗传缺陷。

为了在体外受精(IVF)之后和胚胎着床前遗传诊断和筛查期间选出没有单核苷酸缺陷或染色体异常的胚胎，科研人员把靶向的或全基因组扩增方法与连锁分析结合起来。然而，这种方法常常要涉及对同一胚胎执行多个程序，带来了安全风险。X. Sunney Xie及其同事开发了一种基于下一代DNA测序的方法，称为非整倍体测序和连锁分析揭示突变的等位基因的方法(MARSALA)，从而同时识别出疾病相关的点突变和染色体缺陷，并且对一个5天龄的人类体外受精(IVF)胚胎的活检样本进行了连锁分析。

使用这种MARSALA方法，这组作者筛查了来自两对夫妇的胚胎，其中一对夫妇中的32岁的父亲受到了一个点突变造成的一种遗传型骨病的影响，而另一对夫妇中的33岁的母亲携带有一个x染色体连锁疾病的突变隐性等位基因，该病的标志是毛发、牙齿和汗腺的缺陷。每对夫妇有一个胚胎被植入并且发育到了足月，生出了两个没有继承父母突变的健康女婴，胎儿期羊水细胞分析和对出生后脐带血细胞的DNA测序证实了这一点。

这组作者说，MARSALA方法可能代表了一种在胚胎着床前诊断和筛查体外受精(IVF)胚胎的单基因以及常染色体和性染色体缺陷的准确而具有成本效益的方法。

原文链接：Live births after simultaneous avoidance of monogenic diseases and chromosome abnormality by next-GENEration sequencing with linkage analyses

原文摘要：In vitro fertilization (IVF), preimplantation genetic diagnosis (PGD), and preimplantation genetic screening (PGS) help patients to select embryos free of monogenic diseases and aneuploidy (chromosome abnormality). Next-generation sequencing (NGS) methods, while experiencing a rapid cost reduction, have improved the precision of PGD/PGS. However, the precision of PGD has been limited by the false-positive and false-negative single-nucleotide variations (SNVs), which are not acceptable in IVF and can be circumvented by linkage analyses, such as short tandem repeats or karyomapping. It is noteworthy that existing methods of detecting SNV/copy number variation (CNV) and linkage analysis often require separate procedures for the same embryo. Here we report an NGS-based PGD/PGS procedure that can simultaneously detect a single-gene disorder and aneuploidy and is capable of linkage analysis in a cost-effective way. This method, called “mutated allele revealed by sequencing with aneuploidy and linkage analyses” (MARSALA), involves multiple annealing and looping-based amplification cycles (MALBAC) for single-cell whole-genome amplification. Aneuploidy is determined by CNVs, whereas SNVs associated with the monogenic diseases are detected by PCR amplification of the MALBAC product. The false-positive and -negative SNVs are avoided by an NGS-based linkage analysis. Two healthy babies, free of the monogenic diseases of their parents, were born after such embryo selection. The monogenic diseases originated from a single base mutation on the autosome and the X-chromosome of the disease-carrying father and mother, respectively.

DOI：10.1073/PNAS.1523297113

作者：阳光森林