An 8q24.11q24.13 Microdeletion Encompassing EXT1 in a Boy with Autistic Spectrum Disorder, Intellectual Disability, and Multiple Hereditary Exostoses

der characterized by the growth of multiple osteochondromas in the metaphyses and diaphyses of long bones [1]. MHE is inherited in an autosomal dominant manner. The two causative genes of MHE, exostosin glycosyltransferase 1 (EXT1) and EXT2, are organized as a complex and are both required for heparan sulfate (HS) synthesis. Heterozygous mutations of either EXT gene result in HS deficiency [2]. EXT1 and EXT2 are known to cause exostoses by glycosyltransferases that are involved in the chain elongation step of HS biosynthesis, and HS influences important processes in skeletogenesis, skeletal growth, and morphogenesis [3]. A previous study reported that patients with deletion mutations including 8q24 involving EXT1 sometimes presented with autistic features [4]. HS regulates diverse cell-surface signaling events, and recent research has increasingly uncovered its roles in the development of the nervous system. Here, we describe the case of a boy with a microdeletion (8q24.11q24.13 [118,625,768-124,169,620] ×1), who presented with autism, intellectual disability, and MHE. the parents signed informed consent and approved the anonymous use of pISSN 2635-909X • eISSN 2635-9103 Ann Child Neurol [Epub ahead of print] https://doi.org/10.26815/acn.2021.00451