Amplicon Resequencing Identified Parental Mosaicism for Approximately 10% of “de novo” SCN1A Mutations in Children with Dravet Syndrome |
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Authors: | Xiaojing Xu Xiaoxu Yang Qixi Wu Aijie Liu Xiaoling Yang Adam Yongxin Ye August Yue Huang Jiarui Li Meng Wang Zhe Yu Sheng Wang Zhichao Zhang Xiru Wu Liping Wei Yuehua Zhang |
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Affiliation: | 1. Department of Pediatrics, Peking University First Hospital, Beijing, China;2. Center for Bioinformatics, State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China;3. National Institute of Biological Sciences, Beijing, China;4. Peking‐Tsinghua Center for Life Sciences, Beijing, China;5. Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China;6. College of Biological Sciences, China Agricultural University, Beijing, China;7. Andrology Center, Peking University First Hospital, Beijing, China |
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Abstract: | The majority of children with Dravet syndrome (DS) are caused by de novo SCN1A mutations. To investigate the origin of the mutations, we developed and applied a new method that combined deep amplicon resequencing with a Bayesian model to detect and quantify allelic fractions with improved sensitivity. Of 174 SCN1A mutations in DS probands which were considered “de novo” by Sanger sequencing, we identified 15 cases (8.6%) of parental mosaicism. We identified another five cases of parental mosaicism that were also detectable by Sanger sequencing. Fraction of mutant alleles in the 20 cases of parental mosaicism ranged from 1.1% to 32.6%. Thirteen (65% of 20) mutations originated paternally and seven (35% of 20) maternally. Twelve (60% of 20) mosaic parents did not have any epileptic symptoms. Their mutant allelic fractions were significantly lower than those in mosaic parents with epileptic symptoms (P = 0.016). We identified mosaicism with varied allelic fractions in blood, saliva, urine, hair follicle, oral epithelium, and semen, demonstrating that postzygotic mutations could affect multiple somatic cells as well as germ cells. Our results suggest that more sensitive tools for detecting low‐level mosaicism in parents of families with seemingly “de novo” mutations will allow for better informed genetic counseling. |
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Keywords: | de novo mosaic Dravet syndrome SCN1A next‐generation sequencing somatic mutation |
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