title: Circadian-relevant genes are highly polymorphic in autism spectrum disorder patients.
abstract: BACKGROUND
  The genetic background of autism spectrum disorder (ASD) is considered a multi-genetic disorder with high heritability. Autistic children present with a higher prevalence of sleep disorders than has been observed in children with normal development. Some circadian-relevant genes have been associated with ASD (e.g., PER1, PER2, NPAS2, MTNR1A, and MTNR1B).
  
  
  METHODS
  We analyzed 28 ASD patients (14 with sleep disorders and 14 without) and 23 control subjects of Japanese descent. The coding regions of 18 canonical clock genes and clock-controlled genes were sequenced. Detected mutations were verified by direct sequencing analysis, and additional control individuals were screened.
  
  
  RESULTS
  Thirty-six base changes with amino acid changes were detected in 11 genes. Six missense changes were detected only in individuals with ASD with sleep disturbance: p.F498S in TIMELESS, p.S20R in NR1D1, p.R493C in PER3, p.H542R in CLOCK, p.L473S in ARNTL2, and p.A325V in MTNR1B. Six missense changes were detected only in individuals with ASD without sleep disturbance: p.S1241N in PER1, p.A325T in TIMELESS, p.S13T in ARNTL, p.G24E in MTNR1B, p.G24E in PER2, and p.T1177A in PER3. The p.R493C mutation in PER3 was detected in both groups. One missense change, p.P932L in PER2, was detected only in the control group. Mutations in NR1D1, CLOCK, and ARNTL2 were detected only in individuals with ASD with sleep disorder. The prevalence of the mutations detected only single time differed significantly among all ASD patients and controls (p=0.003). Two kinds of mutations detected only in individuals with ASD with sleep disorder, p.F498S in TIMELESS and p.R366Q in PER3, were considered to affect gene function by three different methods: PolyPhen-2, scale-invariant feature transform (SIFT) prediction, and Mutation Taster (www.mutationtaster.org). The mutations p.S20R in NR1D1, p.H542R in CLOCK, p.L473S in ARNTL2, p.A325T in TIMELESS, p.S13T in ARNTL, and p.G24E in PER2 were diagnosed to negatively affect gene function by more than one of these methods.
  
  
  CONCLUSIONS
  Mutations in circadian-relevant genes affecting gene function are more frequent in patients with ASD than in controls. Circadian-relevant genes may be involved in the psychopathology of ASD.
authors.affiliation: Department of Pediatrics, Jichi Medical University, Shimotsuke, Tochigi, Japan.
authors.forename: Zhiliang
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Department of Pediatrics, Jichi Medical University, Shimotsuke, Tochigi, Japan.
authors.forename: Ayumi
authors.initials: A
authors.lastname: Matsumoto
authors.affiliation: Division of Human Genetics, Center for Molecular Medicine, Jichi Medical University, Shimotsuke, Tochigi, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Nakayama
authors.affiliation: Department of Pediatrics, Jichi Medical University, Shimotsuke, Tochigi, Japan.
authors.forename: Eriko F
authors.initials: EF
authors.lastname: Jimbo
authors.affiliation: Department of Pediatrics, Jichi Medical University, Shimotsuke, Tochigi, Japan.
authors.forename: Karin
authors.initials: K
authors.lastname: Kojima
authors.affiliation: Department of Molecular Neurobiology, Institute for Developmental Research, Aichi Human Service Center, Kasugai, Aichi, Japan.
authors.forename: Koh-ichi
authors.initials: K
authors.lastname: Nagata
authors.affiliation: Division of Human Genetics, Center for Molecular Medicine, Jichi Medical University, Shimotsuke, Tochigi, Japan.
authors.forename: Sadahiko
authors.initials: S
authors.lastname: Iwamoto
authors.affiliation: Department of Pediatrics, Jichi Medical University, Shimotsuke, Tochigi, Japan. Electronic address: takanori@jichi.ac.jp.
authors.forename: Takanori
authors.initials: T
authors.lastname: Yamagata
mesh_terms: D000293:Adolescent; D000328:Adult; D044466:Asian People / Q000235:genetics; D000067877:Autism Spectrum Disorder / Q000150:complications / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D002940:Circadian Rhythm / Q000235:genetics*; D004252:DNA Mutational Analysis; D005260:Female; D006801:Humans; D007564:Japan; D008297:Male; D009154:Mutation; D011110:Polymorphism, Genetic; D012893:Sleep Wake Disorders / Q000150:complications / Q000235:genetics; D055815:Young Adult
keywords: Autism spectrum disorder; Circadian-relevant genes; Mutation; Next-generation sequencing; Period; Single-nucleotide polymorphism; TIMELESS