2-B-P-078 〇橋本 一真¹、三浦 大樹¹、福島 穂高¹、竹本 龍也²、中澤 敬信¹ Kazuma Hashimoto¹, Daiki Miura¹, Hotaka Fukushima¹, Tatsuya Takemoto², Takanobu Nakazawa^{1 1}東農大・院生命・バイオサイエンス、²徳島大・先端酵素学研究所・発生生物 ¹Lab. Mol. Biol., Dept. of Biosci., Grad. Sch. of Life Sci., Tokyo Univ. Agr., ²Lab. Embryo., Inst. Adv. Med. Sci., Tokushima Univ. Circadian rhythms are biological phenomena that regulate the behavior of organisms, fluctuating in approximately 24-hour cycles, and regulate basic physiological functions such as sleep, metabolism, and hormone secretion. Chromosome alignment-maintaining phosphoprotein 1 (CHAMP1) is known as one of the candidate causative genes of intellectual disability (ID). Recent clinical studies have found that patients with ID harboring de novo mutations on the CHAMP1 gene have often sleep difficulties. In this study, we focused on the molecular and cellular mechanisms underlying sleep difficulties. First, we found that the Champ1 gene expression exhibited a time-dependent rhythm when clock genes were synchronized by serum shock in NIH3T3 cells. We also found that the expression level of the Clock gene, one of the clock genes, was decreased when the Champ1 expression was suppressed. Furthermore, we found that the period of a mouse model heterozygous for a CHAMP1 mutation identified in a patient with ID was significantly longer under constant dark conditions in actogram analysis. Our results suggest that sleep difficulties in patients with ID harboring CHAMP1 gene mutations may be due to circadian rhythm dysregulation.