title: Study of the association between 3111T/C polymorphism of the CLOCK gene and the presence of overweight in schoolchildren.
abstract: OBJECTIVE
  To evaluate the association between 3111T/C polymorphism of the CLOCK gene and the presence of obesity and sleep duration in children aged 6-13 years. In adults, this genetic variant has been associated with duration of sleep, ghrelin levels, weight, and eating habits. Although short sleep duration has been linked to obesity in children, no study has aimed to identify the possible molecular mechanisms of this association to date.
  
  
  METHODS
  Weight, height, and circumferences were transformed into Z-scores for age and gender. Genotyping was performed using TaqMan methodology. A questionnaire regarding hours of sleep was provided to parents. The appropriate statistical tests were performed.
  
  
  RESULTS
  This study evaluated 370 children (45% males, 55% females, mean age 8.5 ± 1.5 years). The prevalence of overweight was 18%. The duration of sleep was, on average, 9.7hours, and was inversely related to age (p<0.001). Genotype distribution was: 4% CC, 31% CT, and 65% TT. There was a trend toward higher prevalence of overweight in children who slept less than nine hours (23%) when compared to those who slept more than ten hours (16%, p=0.06). Genotype was not significantly correlated to any of the assessed outcomes.
  
  
  CONCLUSIONS
  The CLOCK 3111T/C polymorphism was not significantly associated with overweight or sleep duration in children in this city.
authors.affiliation: Universidade Vila Velha (UVV), Vila Velha, ES, Brazil.
authors.forename: Nayara P
authors.initials: NP
authors.lastname: Giovaninni
authors.affiliation: Universidade Vila Velha (UVV), Vila Velha, ES, Brazil.
authors.forename: Jeanne T
authors.initials: JT
authors.lastname: Fuly
authors.affiliation: Universidade Vila Velha (UVV), Vila Velha, ES, Brazil.
authors.forename: Leonardo I
authors.initials: LI
authors.lastname: Moraes
authors.affiliation: Universidade Vila Velha (UVV), Vila Velha, ES, Brazil.
authors.forename: Thais N
authors.initials: TN
authors.lastname: Coutinho
authors.affiliation: Universidade de São Paulo, São Paulo, SP, Brazil.
authors.forename: Ericka B
authors.initials: EB
authors.lastname: Trarbach
authors.affiliation: Universidade de São Paulo, São Paulo, SP, Brazil.
authors.forename: Alexander A de L
authors.initials: AA
authors.lastname: Jorge
authors.affiliation: Universidade Vila Velha (UVV), Vila Velha, ES, Brazil. Electronic address: everlayny@gmail.com.
authors.forename: Everlayny F
authors.initials: EF
authors.lastname: Costalonga
mesh_terms: D000293:Adolescent; D000367:Age Factors; D050218:Body Fat Distribution; D056926:CLOCK Proteins / Q000235:genetics*; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D008297:Male; D009765:Obesity / Q000235:genetics*; D050177:Overweight / Q000235:genetics*; D011110:Polymorphism, Genetic / Q000235:genetics*; D012890:Sleep / Q000235:genetics*; D013334:Students; D011795:Surveys and Questionnaires; D013997:Time Factors
chemical_list: D056926:CLOCK Proteins
keywords: CLOCK; Childhood obesity; Duration of sleep; Duração do sono; Obesidade infantil; Polimorfismo; Polymorphism