Zhang Shuo, Pei Zhenle, Lei Caixia, Zhu Saijuan, Deng Ke, Zhou Jing, Yang Jingmin, Lu Daru, Sun Xiaoxi, Xu Chenming, Xu Congjian
Shanghai Ji Ai Genetics & IVF Institute, Shanghai Key Laboratory of Female Reproductive Endocrine Related Diseases, Obstetrics and Gynecology Hospital of Fudan University, Shanghai, China.
State Key Laboratory of Genetic Engineering, School of Life Science, Fudan University, Shanghai, China.
J Med Genet. 2023 Mar;60(3):274-284. doi: 10.1136/jmedgenet-2022-108553. Epub 2022 Jun 16.
Chromosomal rearrangements have profound consequences in diverse human genetic diseases. Currently, the detection of balanced chromosomal rearrangements (BCRs) mainly relies on routine cytogenetic G-banded karyotyping. However, cryptic BCRs are hard to detect by karyotyping, and the risk of miscarriage or delivering abnormal offspring with congenital malformations in carrier couples is significantly increased. In the present study, we aimed to investigate the potential of single-molecule optical genome mapping (OGM) in unravelling cryptic chromosomal rearrangements.
Eleven couples with normal karyotypes that had abortions/affected offspring with unbalanced rearrangements were enrolled. Ultra-high-molecular-weight DNA was isolated from peripheral blood cells and processed via OGM. The genome assembly was performed followed by variant calling and annotation. Meanwhile, multiple detection strategies, including FISH, long-range-PCR amplicon-based next-generation sequencing and Sanger sequencing were implemented to confirm the results obtained from OGM.
High-resolution OGM successfully detected cryptic reciprocal translocation in all recruited couples, which was consistent with the results of FISH and sequencing. All high-confidence cryptic chromosomal translocations detected by OGM were confirmed by sequencing analysis of rearrangement breakpoints. Moreover, OGM revealed additional complex rearrangement events such as inverted aberrations, further refining potential genetic interpretation.
To the best of our knowledge, this is the first study wherein OGM facilitate the rapid and robust detection of cryptic chromosomal reciprocal translocations in clinical practice. With the excellent performance, our findings suggest that OGM is well qualified as an accurate, comprehensive and first-line method for detecting cryptic BCRs in routine clinical testing.
染色体重排在多种人类遗传疾病中具有深远影响。目前，平衡染色体重排（BCR）的检测主要依赖于常规细胞遗传学G带核型分析。然而，隐匿性BCR很难通过核型分析检测到，并且携带平衡染色体重排的夫妇发生流产或生出有先天性畸形的异常后代的风险显著增加。在本研究中，我们旨在探讨单分子光学基因组图谱（OGM）在揭示隐匿性染色体重排方面的潜力。
招募了11对核型正常但有流产/不平衡重排的患病后代的夫妇。从外周血细胞中分离出超高分子量DNA，并通过OGM进行处理。进行基因组组装，随后进行变异检测和注释。同时，实施了多种检测策略，包括荧光原位杂交（FISH）、基于长链PCR扩增子的下一代测序和桑格测序，以确认从OGM获得的结果。
高分辨率OGM成功检测到所有招募夫妇中的隐匿性相互易位，这与FISH和测序结果一致。OGM检测到的所有高置信度隐匿性染色体重排均通过重排断点的测序分析得到证实。此外，OGM还揭示了其他复杂的重排事件，如倒位畸变，进一步完善了潜在的遗传解释。
据我们所知，这是第一项表明OGM在临床实践中有助于快速、可靠地检测隐匿性染色体相互易位的研究。基于其出色的性能，我们的研究结果表明OGM完全有资格作为常规临床检测中检测隐匿性BCR的准确、全面的一线方法。
