Nava-Trujillo Hector, Rivera Rocío Melissa
Division of Animal Sciences, University of Missouri, Columbia, MO 65211, USA.
Division of Animal Sciences, University of Missouri, Columbia, MO 65211, USA.
Animal. 2023 May;17 Suppl 1:100740. doi: 10.1016/j.animal.2023.100740.
Large/abnormal Offspring Syndrome (LOS/AOS) is a congenital overgrowth condition of cattle and sheep, characterized by macrosomia, abdominal wall defects, organomegaly, difficulty to stand and suckle at parturition. The condition was first described as an exclusive consequence of assisted reproductive technologies, such as in vitro production and somatic cell nuclear transfer (cloning). However, we recently reported the spontaneous occurrence of this syndrome in cattle. The etiology of LOS is unclear, although the syndrome is an epigenetic condition characterized by multi-locus loss-of-imprinting, global dysregulation of small and long RNAs, changes in DNA methylation, and altered chromosomal architecture. These molecular and epigenetic changes affect biological pathways implicated in organ size, cell proliferation, cell survival, resulting in the phenotypes which characterize LOS. The lack of accurate tools for the prediction and diagnosis of LOS and the prevention of dystocia resulting from fetal overgrowth is a major concern for the dairy and beef industries. Furthermore, death of the calf and/or dam during calving adds animal welfare issues and affects the net income of the industry. An early diagnosis of LOS/AOS during gestation is critical to facilitate the decision-making process on whether to allow the pregnancy to continue or not in order to prevent harm to the dam as well as to provide producers with the timely necessary information to prepare for a difficult birth. The present review summarizes the definition, traits, incidence, and molecular characteristics of LOS to provide information and serve as a guide for future investigations regarding the early identification of LOS during pregnancy in cattle.
大/异常后代综合征（LOS/AOS）是牛和羊的一种先天性过度生长疾病，其特征为巨大儿、腹壁缺陷、器官肿大、分娩时站立和吮乳困难。该病症最初被描述为体外生产和体细胞核移植（克隆）等辅助生殖技术的唯一后果。然而，我们最近报道了牛群中该综合征的自发发生情况。LOS的病因尚不清楚，尽管该综合征是一种表观遗传病症，其特征为多位点印记丢失、小RNA和长RNA的整体失调、DNA甲基化变化以及染色体结构改变。这些分子和表观遗传变化影响与器官大小、细胞增殖、细胞存活相关的生物学途径，从而导致LOS的特征性表型。缺乏用于预测和诊断LOS以及预防胎儿过度生长导致难产的准确工具，是乳制品和牛肉行业的主要担忧。此外，产犊期间犊牛和/或母牛的死亡增加了动物福利问题，并影响该行业的净收入。妊娠期对LOS/AOS进行早期诊断对于促进关于是否允许妊娠继续的决策过程至关重要，以便防止对母牛造成伤害，并为生产者提供及时的必要信息，为难产做好准备。本综述总结了LOS的定义、特征、发病率和分子特征，以提供信息并为未来关于牛妊娠期间LOS早期识别的研究提供指导。
