Circadian system heritability as assessed by wrist temperature: A twin study

Abstract

Previous research shows that wrist temperature (WT) is a good marker to assess the circadian system health in different circumstances. However, no studies have been performed in order to know the genetic component of this circadian marker. For this purpose, the aim was to determine, using classical twin models, the relative genetic and environmental influences on WT. The study was performed in 53 pairs of female twins (28 monozygotic (MZ) and 25 dizygotic (DZ)), with a body mass index 25.9 ± 3.78 and mean age 52 ± 6 years. The sample was selected from the Murcia Twin Register. Circadian patterns were studied by analyzing WT during one week every 10 min “Circadianware®”. Genetic influences to WT variability were estimated by comparing correlations of MZ and DZ twin pairs and fitting genetic structural equation models to measured variables. MZ twins showed higher intra-pair correlations than DZ twins for most of the parameters. Genetic factors were responsible for between 46% and 70% of variance (broad sense heritability) in parameters such as mean temperature, mesor, acrophase, Rayleigh test, percentage of rhythmicity and five hours of maximum temperature. The pattern of correlations and the genetic models point to moderate to high heritability for most of the WT parameters, suggesting a relevant genetic influence. The presence of these genetic factors points to endogenicity as the main cause of the coincidence of the WT rhythms. However, some WT parameters are still dependent on environment to a relevant extent and, hence, more amenable to change through external interventions.

• Chronobiology
• circadian rhythms
• heritability
• twins
• wrist temperature

Declaration of Interest

Authors fully declare any financial or other potential conflict of interest.

This work was supported by The Spanish Government of Science and Innovation (project no. BFU2011-24720), Seneca Foundation (Project No. 15123/PI/10), the Ministry of Economy and Competitiveness and the Instituto de Salud Carlos III – RETICEF (The Ageing and Frailty Cooperative Research Network, RD12/0043/0011), the Ministry of Education and Science and the Ministry of Economy and Competitiveness (BFU2010-21945-C02-01, IPT-2011-0833-900000), including FEDER co-funding granted to J. A. Madrid. The Murcia Twin Registry is supported by the Seneca Foundation, the Regional Agency for Science and Technology, Murcia, Spain (15302/PHCS/10) and the Ministry of Science and Innovation, Spain (PSI11560–2009).