Profiling PI3K-AKT-MTOR variants in focal brain malformations reveals new insights for diagnostic care

作者：Filomena Pirozzi, Matthew Berkseth, Rylee Shear, Lorenzo Gonzalez, Andrew E. Timms, Josef Šulc, Emily Pao, Nora Oyama, Francesca Forzano, Valerio Conti, Renzo Guerrini, Emily S Doherty, Sulagna C. Saitta, Christina M. Lockwood, Colin C. Pritchard, William B. Dobyns, Edward J. Novotny, Jason N. Wright, Russell P. Saneto, Seth D. Friedman, Jason S. Hauptman, Jeffrey G. Ojemann, Raj P. Kapur, Ghayda Mirzaa · 发表于：Brain · 年份：2021 · DOI：10.1093/brain/awab376 · 被引用次数：55 · 研究领域：Renal and related cancers、Genomics and Rare Diseases、Epilepsy research and treatment

Focal malformations of cortical development including focal cortical dysplasia, hemimegalencephaly and megalencephaly, are a spectrum of neurodevelopmental disorders associated with brain overgrowth, cellular and architectural dysplasia, intractable epilepsy, autism and intellectual disability. Importantly, focal cortical dysplasia is the most common cause of focal intractable paediatric epilepsy. Gain and loss of function variants in the PI3K-AKT-MTOR pathway have been identified in this spectrum, with variable levels of mosaicism and tissue distribution. In this study, we performed deep molecular profiling of common PI3K-AKT-MTOR pathway variants in surgically resected tissues using droplet digital polymerase chain reaction (ddPCR), combined with analysis of key phenotype data. A total of 159 samples, including 124 brain tissue samples, were collected from 58 children with focal malformations of cortical development. We designed an ultra-sensitive and highly targeted molecular diagnostic panel using ddPCR for six mutational hotspots in three PI3K-AKT-MTOR pathway genes, namely PIK3CA (p.E542K, p.E545K, p.H1047R), AKT3 (p.E17K) and MTOR (p.S2215F, p.S2215Y). We quantified the level of mosaicism across all samples and correlated genotypes with key clinical, neuroimaging and histopathological data. Pathogenic variants were identified in 17 individuals, with an overall molecular solve rate of 29.31%. Variant allele fractions ranged from 0.14 to 22.67% across all mutation-positi...