title: Clock polymorphisms and circadian rhythms phenotypes in a sample of the Brazilian population.
abstract: A Clock polymorphism T to C situated in the 3' untranslated region (3'-UTR) has been associated with human diurnal preference. At first, Clock 3111C had been reported as a marker for evening preference. However these data are controversial, and data both corroborating and denying them have been reported. This study hypothesizes that differences in Clock genotypes could be observed if extreme morning-type subjects were compared with extreme evening-type subjects, and the T3111C and T257G polymorphisms were studied. The possible relationship between both polymorphisms and delayed sleep phase syndrome (DSPS) was also investigated. An interesting and almost complete linkage disequilibrium between the polymorphisms T257G in the 5' UTR region and the T3111C in the 3' UTR region of the Clock gene is described. Almost always, a G in position 257 corresponds to a C in position 3111, and a T in position 257 corresponds to a T in position 3111. The possibility of an interaction of these two regions in the Clock messenger RNA structure that could affect gene expression was analyzed using computer software. The analyses did not reveal an interaction between those two regions, and it is unlikely that this full allele correspondence affects Clock gene expression. These results show that there is no association between either polymorphism T3111C or T257G in the Clock gene with diurnal preference or delayed sleep phase syndrome (DSPS). These controversial data could result from the possible effects of latitude and clock genes interaction on circadian phenotypes.
authors.affiliation: Department of Psychobiology/Sleep Institute, Universidade Federal de São Paulo, SP, Brazil. epedrazzo@psicobio.epm.br
authors.forename: Mario
authors.initials: M
authors.lastname: Pedrazzoli
authors.forename: Fernando Mazzili
authors.initials: FM
authors.lastname: Louzada
authors.forename: Danyella Silva
authors.initials: DS
authors.lastname: Pereira
authors.forename: Ana Amélia
authors.initials: AA
authors.lastname: Benedito-Silva
authors.forename: Alberto Remesar
authors.initials: AR
authors.lastname: Lopez
authors.forename: Bruno Jacson
authors.initials: BJ
authors.lastname: Martynhak
authors.forename: Anna Ligia
authors.initials: AL
authors.lastname: Korczak
authors.forename: Bruna Del Vechio
authors.initials: Bdel V
authors.lastname: Koike
authors.forename: Ana Alves
authors.initials: AA
authors.lastname: Barbosa
authors.forename: Vania
authors.initials: V
authors.lastname: D'Almeida
authors.forename: Sergio
authors.initials: S
authors.lastname: Tufik
mesh_terms: D000328:Adult; D000596:Amino Acids / Q000235:genetics; D001938:Brazil; D056926:CLOCK Proteins; D002940:Circadian Rhythm / Q000235:genetics*; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D008297:Male; D009690:Nucleic Acid Conformation; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D012333:RNA, Messenger / Q000737:chemistry; D015534:Trans-Activators / Q000235:genetics*
chemical_list: D000596:Amino Acids; D012333:RNA, Messenger; D015534:Trans-Activators; D056926:CLOCK Proteins; C538943:CLOCK protein, human