Ye Zimeng, Lin Sufang, Zhao Xia, Bennett Mark F, Brown Natasha J, Wallis Mathew, Gao Xinyi, Sun Li, Wu Jiarui, Vedururu Ravikiran, Witkowski Tom, Gardiner Fiona, Stutterd Chloe, Duan Jing, Mullen Saul A, McGillivray George, Bodek Simon, Valente Giulia, Reagan Matthew, Yao Yi, Li Lin, Chen Li, Boys Amber, Adikari Thiuni N, Cao Dezhi, Hu Zhanqi, Beshay Victoria, Zhang Victor W, Berkovic Samuel F, Scheffer Ingrid E, Liao Jianxiang, Hildebrand Michael S
Epilepsy Research Centre, Department of Medicine, The University of Melbourne, Heidelberg, Victoria, Australia.
Department of Neurology, Epilepsy Centre, Shenzhen Children's Hospital, Shenzhen, Guangdong Province, China.
Hum Mutat. 2022 Dec;43(12):1956-1969. doi: 10.1002/humu.24454. Epub 2022 Sep 6.
Tuberous sclerosis complex (TSC) is a multi-system genetic disorder. Most patients have germline mutations in TSC1 or TSC2 but, 10%-15% patients do not have TSC1/TSC2 mutations detected on routine clinical genetic testing. We investigated the contribution of low-level mosaic TSC1/TSC2 mutations in unsolved sporadic patients and families with TSC. Thirty-one sporadic TSC patients negative on routine testing and eight families with suspected parental mosaicism were sequenced using deep panel sequencing followed by droplet digital polymerase chain reaction. Pathogenic variants were found in 22/31 (71%) unsolved sporadic patients, 16 were mosaic (median variant allele fraction [VAF] 6.8% in blood) and 6 had missed germline mutations. Parental mosaicism was detected in 5/8 families (median VAF 1% in blood). Clinical testing laboratories typically only report pathogenic variants with allele fractions above 10%. Our findings highlight the critical need to change laboratory practice by implementing higher sensitivity assays to improve diagnostic yield, inform patient management and guide reproductive counseling.
结节性硬化症复合体（TSC）是一种多系统遗传性疾病。大多数患者在TSC1或TSC2基因中有生殖系突变，但10%-15%的患者在常规临床基因检测中未检测到TSC1/TSC2突变。我们研究了未确诊的散发性TSC患者和家庭中低水平镶嵌性TSC1/TSC2突变的作用。对31例常规检测呈阴性的散发性TSC患者和8个疑似亲本镶嵌性的家庭进行了深度测序，随后进行液滴数字聚合酶链反应。在22/31（71%）未确诊的散发性患者中发现了致病变异，其中16例为镶嵌性（血液中变异等位基因分数[VAF]中位数为6.8%），6例有遗漏的生殖系突变。在5/8的家庭中检测到亲本镶嵌性（血液中VAF中位数为1%）。临床检测实验室通常只报告等位基因分数高于10%的致病变异。我们的研究结果突出表明，迫切需要通过实施更高灵敏度的检测方法来改变实验室操作，以提高诊断率、为患者管理提供信息并指导生殖咨询。
