Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Division of Genetics and Genomics, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA; Division of Newborn Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.
Department of Medicine, Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA.
Am J Hum Genet. 2023 Aug 3;110(8):1229-1248. doi: 10.1016/j.ajhg.2023.06.009.
Despite advances in clinical genetic testing, including the introduction of exome sequencing (ES), more than 50% of individuals with a suspected Mendelian condition lack a precise molecular diagnosis. Clinical evaluation is increasingly undertaken by specialists outside of clinical genetics, often occurring in a tiered fashion and typically ending after ES. The current diagnostic rate reflects multiple factors, including technical limitations, incomplete understanding of variant pathogenicity, missing genotype-phenotype associations, complex gene-environment interactions, and reporting differences between clinical labs. Maintaining a clear understanding of the rapidly evolving landscape of diagnostic tests beyond ES, and their limitations, presents a challenge for non-genetics professionals. Newer tests, such as short-read genome or RNA sequencing, can be challenging to order, and emerging technologies, such as optical genome mapping and long-read DNA sequencing, are not available clinically. Furthermore, there is no clear guidance on the next best steps after inconclusive evaluation. Here, we review why a clinical genetic evaluation may be negative, discuss questions to be asked in this setting, and provide a framework for further investigation, including the advantages and disadvantages of new approaches that are nascent in the clinical sphere. We present a guide for the next best steps after inconclusive molecular testing based upon phenotype and prior evaluation, including when to consider referral to research consortia focused on elucidating the underlying cause of rare unsolved genetic disorders.
尽管临床基因检测取得了进展，包括外显子组测序（ES）的引入，但仍有超过 50%的疑似孟德尔疾病患者无法获得精确的分子诊断。临床评估越来越多地由临床遗传学以外的专家进行，通常以分层的方式进行，通常在 ES 之后结束。目前的诊断率反映了多种因素，包括技术限制、对变异致病性的理解不完整、基因型-表型关联缺失、复杂的基因-环境相互作用以及临床实验室之间的报告差异。对于非遗传学专业人员来说，了解 ES 之外的诊断测试及其局限性的快速发展的领域，并了解其局限性，是一项挑战。新的测试，如短读长基因组或 RNA 测序，可能难以订购，而新兴技术，如光学基因组图谱和长读 DNA 测序，目前尚未在临床上使用。此外，对于不确定评估之后的下一步最佳步骤，尚无明确的指导。在这里，我们回顾了为什么临床遗传评估可能是阴性的，讨论了在这种情况下要提出的问题，并提供了进一步调查的框架，包括新兴的临床领域中具有优势和劣势的新方法。我们根据表型和先前的评估，为不确定的分子检测之后的下一步提供了指南，包括何时考虑转介给专注于阐明罕见未解决遗传疾病根本原因的研究联盟。
