Department of Internal Medicine, Reproduction and Population Medicine, Ghent University, Merelbeke, Belgium.
Department of Human Genetics, KU Leuven, Leuven, Belgium.
Sci Rep. 2024 Jan 23;14(1):2003. doi: 10.1038/s41598-023-48103-7.
In different species, embryonic aneuploidies and genome-wide errors are a major cause of developmental failure. The increasing number of equine embryos being produced worldwide provides the opportunity to characterize and rank or select embryos based on their genetic profile prior to transfer. Here, we explored the possibility of generic, genome-wide preimplantation genetic testing concurrently for aneuploidies (PGT-A) and monogenic (PGT-M) traits and diseases in the horse, meanwhile assessing the incidence and spectrum of chromosomal and genome-wide errors in in vitro-produced equine embryos. To this end, over 70,000 single nucleotide polymorphism (SNP) positions were genotyped in 14 trophectoderm biopsies and corresponding biopsied blastocysts, and in 26 individual blastomeres from six arrested cleavage-stage embryos. Subsequently, concurrent genome-wide copy number detection and haplotyping by haplarithmisis was performed and the presence of aneuploidies and genome-wide errors and the inherited parental haplotypes for four common disease-associated genes with high carrier frequency in different horse breeds (GBE1, PLOD1, B3GALNT2, MUTYH), and for one color coat-associated gene (STX17) were compared in biopsy-blastocyst combinations. The euploid (n = 12) or fully aneuploid (n = 2) state and the inherited parental haplotypes for 42/45 loci of interest of the biopsied blastocysts were predicted by the biopsy samples in all successfully analyzed biopsy-blastocyst combinations (n = 9). Two biopsies showed a loss of maternal chromosome 28 and 31, respectively, which were confirmed in the corresponding blastocysts. In one of those biopsies, additional complex aneuploidies not present in the blastocyst were found. Five out of six arrested embryos contained chromosomal and/or genome-wide errors in most of their blastomeres, demonstrating their contribution to equine embryonic arrest in vitro. The application of the described PGT strategy would allow to select equine embryos devoid of genetic errors and pathogenetic variants, and with the variants of interest, which will improve foaling rate and horse quality. We believe this approach will be a gamechanger in horse breeding.
在不同物种中，胚胎非整倍体和全基因组错误是发育失败的主要原因。全世界生产的马胚胎数量不断增加，为在转移前根据其遗传特征对胚胎进行特征描述、分级或选择提供了机会。在这里，我们探索了在马中同时进行全基因组非整倍体（PGT-A）和单基因（PGT-M）检测的可能性，以检测和评估体外生产的马胚胎中染色体和全基因组错误的发生率和范围。为此，对 14 个滋养层活检和相应的活检囊胚以及 6 个停滞的卵裂期胚胎的 26 个单个卵裂球中的超过 70,000 个单核苷酸多态性（SNP）位置进行了基因分型。随后，通过 haplarithmisis 进行了全基因组拷贝数检测和单倍型分析，并比较了活检囊胚组合中 4 个常见与疾病相关的高携带频率基因（GBE1、PLOD1、B3GALNT2、MUTYH）和 1 个毛色相关基因（STX17）的非整倍体和全基因组错误以及遗传的亲本单倍型。在所有成功分析的活检囊胚组合（n=9）中，通过活检样本预测了活检囊胚的 42/45 个感兴趣的基因座的整倍体（n=12）或完全非整倍体（n=2）状态和遗传的亲本单倍型。两个活检样本分别显示出母染色体 28 和 31 的丢失，这在相应的囊胚中得到了证实。在其中一个活检样本中，还发现了不存在于囊胚中的额外复杂非整倍体。六个停滞胚胎中的五个在大多数卵裂球中都存在染色体和/或全基因组错误，这表明它们在体外对马胚胎停滞的贡献。描述的 PGT 策略的应用将允许选择没有遗传错误和致病性变异的马胚胎，以及具有感兴趣的变异，这将提高产仔率和马的质量。我们相信，这种方法将改变马的繁殖方式。
