Circadian clock gene variants in two Japanese families with familial advanced sleep phase

Extract

Familial advanced sleep phase (FASP) is characterized by extremely early sleep–wake patterns [1, 2]. Although individuals with FASP experience early morning awakenings, they adapt relatively easily to general social life compared with individuals with delayed sleep–wake phase disorder or non-24-hour sleep–wake rhythm disorder. Several familial cases of FASP have been reported, and six genetic variants in the circadian clock genes have been shown to be associated with FASP (Supplementary Table 1) [3–8]. We have previously screened two Japanese families with FASP for the PERIOD2 (PER2) variant (PER2 S662G) initially reported in a Caucasian family with FASP [5], and did not detect the PER2 variant [6]. In this study, we performed targeted sequencing of 76 genes in 15 individuals from our two FASP families. This study was approved by the Ethics Committee of the National Center of Neurology and Psychiatry and was conducted in accordance with the Declaration of Helsinki. Written informed consent was obtained from each subject.