Matsubara Keiko, Yanagida Kaede, Nagai Toshiro, Kagami Masayo, Fukami Maki
Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo, Japan.
MK Clinic, Miyakonojo, Japan.
Front Genet. 2020 Feb 27;11:132. doi: 10.3389/fgene.2020.00132. eCollection 2020.
Small supernumerary marker chromosomes (SMCs) are rare cytogenetic abnormalities. small SMCs, particularly those combined with uniparental disomy (UPD), are assumed to result from incomplete trisomy rescue. Recently, a one-off cellular event designated as chromothripsis was reported as a mechanism for trisomy rescue in micronuclei. This article aims to highlight a possible association among trisomy rescue, chromothripsis, and SMCs. We propose that chromothripsis-mediated incomplete trisomy rescue in micronuclei underlies various chromosomal rearrangements including SMCs, although other mechanisms such as U-type exchange may also yield SMCs. These assumptions are primarily based on observations of previously reported patients with complex rearrangements and our patient with a small SMC. Given the high frequency of trisomic cells in human preimplantation embryos, chromothripsis-mediated trisomy rescue may be a physiologically important phenomenon. Nevertheless, trisomy rescue has a potential to produce UPD, SMCs, and other chromosomal rearrangements. The concepts of trisomy rescue, chromothripsis, and micronuclei provide novel insights into the mechanism for the maintenance and modification of human chromosomes.
小额外标记染色体（SMCs）是罕见的细胞遗传学异常。小的SMCs，尤其是那些与单亲二体性（UPD）相关的，被认为是由不完全三体拯救导致的。最近，一种被称为染色体碎裂的一次性细胞事件被报道为微核中三体拯救的一种机制。本文旨在强调三体拯救、染色体碎裂和SMCs之间可能存在的关联。我们提出，微核中染色体碎裂介导的不完全三体拯救是包括SMCs在内的各种染色体重排的基础，尽管其他机制如U型交换也可能产生SMCs。这些假设主要基于对先前报道的复杂重排患者以及我们的携带小SMCs的患者的观察。鉴于人类植入前胚胎中三体细胞的高频率，染色体碎裂介导的三体拯救可能是一种生理上重要的现象。然而，三体拯救有可能产生UPD、SMCs和其他染色体重排。三体拯救、染色体碎裂和微核的概念为人类染色体的维持和修饰机制提供了新的见解。
