Mutations in HECW2 are associated with intellectual disability and epilepsy
JOURNAL OF MEDICAL GENETICS
Authors: Halvardson, Jonatan; Zhao, Jin J.; Zaghlool, Ammar; Wentzel, Christian; Georgii-Hemming, Patrik; Mansson, Else; Ederth Saevmarker, Helena; Brandberg, Goeran; Soussi Zander, Cecilia; Thuresson, Ann-Charlotte; Feuk, Lars
Abstract
Background De novo mutations are a frequent cause of disorders related to brain development. We report the results of screening patients diagnosed with both epilepsy and intellectual disability (ID) using exome sequencing to identify known and new causative de novo mutations relevant to these conditions. Methods Exome sequencing was performed on 39 patient-parent trios to identify de novo mutations. Clinical significance of de novo mutations in genes was determined using the American College of Medical Genetics and Genomics standard guidelines for interpretation of coding variants. Variants in genes of unknown clinical significance were further analysed in the context of previous trio sequencing efforts in neurodevelopmental disorders. Results In 39 patient-parent trios we identified 29 de novo mutations in coding sequence. Analysis of de novo and inherited variants yielded a molecular diagnosis in 11 families (28.2%). In combination with previously published exome sequencing results in neurodevelopmental disorders, our analysis implicates HECW2 as a novel candidate gene in ID and epilepsy. Conclusions Our results support the use of exome sequencing as a diagnostic approach for ID and epilepsy, and confirm previous results regarding the importance of de novo mutations in this patient group. The results also highlight the utility of network analysis and comparison to previous large-scale studies as strategies to prioritise candidate genes for further studies. This study adds knowledge to the increasingly growing list of causative and candidate genes in ID and epilepsy and highlights HECW2 as a new candidate gene for neurodevelopmental disorders.
Association of HECW2 variants with developmental and epileptic encephalopathy and knockdown of zebrafish hecw2a
AMERICAN JOURNAL OF MEDICAL GENETICS PART A
Authors: Lu, Qian; Zhang, Meng-Na; Shi, Xiu-Yu; Zhang, Ling-Qiang; Wang, Yang-Yang; Liu, Li-Ying; He, Wen; Chen, Hui-Min; He, Bing; Zou, Li-Ping
Abstract
Developmental and epileptic encephalopathy (DEE) is a severe encephalopathy in infants and early childhood. In this study we reported a recurrent de novo variant (c.3985C>T, p.R1330W) in HECW2 (HECT, C2 and WW domain containing E3 ubiquitin protein ligase 2) (MIM# 617245) identified by screening 240 patients with DEE and summarized clinical features of published DEE patients with HECW2 variants. Functionally, transcriptional knockdown of zebrafish hecw2a led to early morphological abnormalities in the brain tissues. These results suggest a potential functional link between HECW2 dysfunction and brain development.