Tehran University of Medical Sciences Acta Medica Iranica 0044-6025 56 10 2019 01 13 677 680 EN Amene Saghazadeh Research Center for Immunodeficiencies, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran. AND Meta Cognition Interest Group (MCIG), Universal Scientific Education and Research Network (USERN), Tehran, Iran Seyed Hassan Tonekaboni Pediatric Neurology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Hossein Najmabadi Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Evin, Tehran, Iran. AND Kariminejad-Najmabaadi Pathology and Genetics Laboratory, Tehran, Iran. Nima Rezaei Research Center for Immunodeficiencies, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran. AND Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran. AND Systematic Review and Meta-Analysis Expert Group (SRMEG), Universal Scientific Education and Research Network (USERN), Tehran, Iran. 2018 03 31 2018 11 05 The ATP8A2 protein is mainly located in the brain and takes part in the lipid flipping process. Mutations in the ATP8A2 gene and chromosomal translocations that interfere with the ATP8A2 gene product have been reported in association with global developmental delay and hypotonia. Here, we will report a three-year-old male presented with major phenotypic features of dysequilibrium syndrome (DES), including severe hypotonia, global developmental delay, speech problem, and strabismus. Whole exome sequencing revealed a homozygous in-frame deletion in the ATP8A2 gene (c.1286_1288delAGA, p.Lys429del). This ATP8A2 variant has not been reported yet and seems to be linked to the phenotypic features of dysequilibrium syndrome. https://acta.tums.ac.ir/index.php/acta/article/view/7153 https://acta.tums.ac.ir/index.php/acta/article/download/7153/5174