Chupong Ittiwut1, Sathida Poonmaksatit2, Ponghatai Boonsimma1, Tayard Desudchit2, Kanya Suphapeetiporn1, Rungnapa Ittiwut3, Vorasuk Shotelersuk1. 1. Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand; Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, the Thai Red Cross Society, Bangkok 10330, Thailand. 2. Division of Neurology, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand. 3. Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand; Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, the Thai Red Cross Society, Bangkok 10330, Thailand. Electronic address: rungnapa.i@chulahospital.org.
Abstract
BACKGROUND: In approximately half of patients with epilepsy and intellectual disability (ID), the cause is unidentified and could be a mutation in a new disease gene. PATIENT DESCRIPTION: To determine the discovery of disease-causing mutation in a female patient with epilepsy and ID, we performed trio whole-exome sequencing, reverse transcription polymerase chain reaction (RT-PCR) followed by Sanger sequencing. RESULTS: Trio whole-exome sequencing was performed and revealed a novel de novo heterozygous stop-loss c.467A > T (p.*156Leuext*35) mutation in the ATP6V0C gene. Using RNA from leukocytes, RT-PCR followed by Sanger sequencing showed the existence of the mutant RNA, and real-time PCR demonstrated that the patient's ATP6V0C RNA level was approximately half of that in her parents, suggesting haploinsufficiency as a pathomechanism. CONCLUSION: These findings, along with previous reports of individuals with similar phenotypes and variants in the same gene, substantiate ATP6V0C as a gene causing epilepsy with ID.
BACKGROUND: In approximately half of patients with epilepsy and intellectual disability (ID), the cause is unidentified and could be a mutation in a new disease gene. PATIENT DESCRIPTION: To determine the discovery of disease-causing mutation in a female patient with epilepsy and ID, we performed trio whole-exome sequencing, reverse transcription polymerase chain reaction (RT-PCR) followed by Sanger sequencing. RESULTS: Trio whole-exome sequencing was performed and revealed a novel de novo heterozygous stop-loss c.467A > T (p.*156Leuext*35) mutation in the ATP6V0C gene. Using RNA from leukocytes, RT-PCR followed by Sanger sequencing showed the existence of the mutant RNA, and real-time PCR demonstrated that the patient's ATP6V0C RNA level was approximately half of that in her parents, suggesting haploinsufficiency as a pathomechanism. CONCLUSION: These findings, along with previous reports of individuals with similar phenotypes and variants in the same gene, substantiate ATP6V0C as a gene causing epilepsy with ID.