Meyer Stefanie, Kaulfuß Silke, Zechel Sabrina, Kummer Karsten, Seif Amir Hosseini Ali, Ernst Marielle Sophie, Schmidt Jens, Pauli Silke, Zschüntzsch Jana
Department of Neurology, University Medical Center Göttingen, Göttingen, Germany.
Department of Human Genetics, University Medical Center Göttingen, Göttingen, Germany.
Front Neurol. 2022 Jul 19;13:893605. doi: 10.3389/fneur.2022.893605. eCollection 2022.
Benefits and challenges resulting from advances in genetic diagnostics are two sides of the same coin. Facilitation of a correct and timely diagnosis is paralleled by challenges in interpretation of variants of unknown significance (VUS). Focusing on an individual VUS-re-classification pipeline, this study offers a diagnostic approach for clinically suspected hereditary muscular dystrophy by combining the expertise of an interdisciplinary team.
In a multi-step approach, a thorough phenotype assessment including clinical examination, laboratory work, muscle MRI and histopathological evaluation of muscle was performed in combination with advanced Next Generation Sequencing (NGS). Different in-silico tools and prediction programs like Alamut, SIFT, Polyphen, MutationTaster and M-Cap as well as 3D- modeling of protein structure and RNA-sequencing were employed to determine clinical significance of the variants.
Two previously unknown sequence alterations in were detected, a missense variant was classified initially according to ACMG guidelines as a VUS (class 3) whereas a second splice site variant was deemed as likely pathogenic (class 4). Pathogenicity of the splice site variant was confirmed by mRNA sequencing and nonsense mediated decay (NMD) was detected. Combination of the detected variants could be associated to the LGMDR23-phenotype based on the MRI matching and literature research.
Two novel variants in associated with LGMDR23-phenotype are described. This study illustrates challenges of the genetic findings due to their VUS classification and elucidates how individualized diagnostic procedure has contributed to the accurate diagnosis in the spectrum of LGMD.
基因诊断进展带来的益处和挑战是同一枚硬币的两面。在促进正确及时诊断的同时，对意义未明变异（VUS）的解读也面临挑战。本研究聚焦于个体VUS重新分类流程，通过跨学科团队的专业知识结合，为临床疑似遗传性肌肉营养不良提供了一种诊断方法。
采用多步骤方法，结合先进的二代测序（NGS），对包括临床检查、实验室检查、肌肉MRI和肌肉组织病理学评估在内的全面表型进行评估。使用不同的电子工具和预测程序，如Alamut、SIFT、Polyphen、MutationTaster和M-Cap，以及蛋白质结构的三维建模和RNA测序，来确定变异的临床意义。
检测到两个先前未知的序列改变，一个错义变异最初根据美国医学遗传学与基因组学学会（ACMG）指南被分类为VUS（3类），而另一个剪接位点变异被认为可能致病（4类）。通过mRNA测序证实了剪接位点变异的致病性，并检测到无义介导的衰变（NMD）。基于MRI匹配和文献研究，检测到的变异组合可能与LGMDR23表型相关。
描述了两个与LGMDR23表型相关的新变异。本研究说明了由于VUS分类导致的基因发现挑战，并阐明了个体化诊断程序如何有助于在肢带型肌营养不良（LGMD）谱系中进行准确诊断。
