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Wednesday, June 6th., 2018

INMA: "A European study combines novel population-based molecular genetic methods to investigate associations with sleep duration in children"

Sleep duration is an indicator of sleep need and overall well-being. The effects of sleeping insufficient or excessive hours have already been widely studied, having found strong associations with a variety of medical and psychosocial problems. However, what are the biological mechanisms behind these associations? It is still unknown whether common genetic variants in individuals explain to some extent sleep duration in children, and whether these genetic variants indicate a biological mechanism, which reveals the role of sleep duration in health and disease.

To address this issue, a Genome-Wide Association Study was performed, in combination with novel population based-molecular genetic methods. The authors evaluated the association and heritability of genetic variants with sleep duration, as well as their relationship with metabolic and psychiatric traits. Children aged 2 to 14 years were included in the study. The discovery phase consisted of five European cohorts: one from United Kingdom, one from Germany, one from the Netherlands and two from Spain. Among them, the Sabadell, Valencia and Menorca INMA cohorts were included. The replication phase consisted of two additional cohorts: one from Finland and another one from the Netherlands. This study was the largest to date with genetic data using these methods.

The study identified a novel chromosome region (11q13.4) associated with sleep duration, however, this discovery was not replicated in the posterior phase, i.e., it was not detected when analyzing the same association in the other two cohorts. The study also observed a moderate heritability of the sleep duration in children. Finally, this study found evidence for an association between sleep duration and type 2 diabetes, which could suggest a common pathogenic mechanism.

According to the authors, the number of participants in the replication phase was probably small to confirm the discovery of the new chromosome region. In this type of studies, it is very important to consider a great number of participants to observe associations and to replicate results in other populations to confirm the findings. This study gives input to new genetic research about sleep duration in children, to unravel the genetic mechanisms associating sleep duration with health.

REFERENCE: Marinelli M, Pappa I, Bustamante M, Bonilla C, Suarez A, Tiesler CM, Vilor-Tejedor N, Zafarmand MH, Alvarez-Pedrerol M, Andersson S, Bakermans-Kranenburg MJ, Estivill X, Evans DM, Flexeder C, Fons J, Gonzalez JR, Guxens M, Huss A, van IJzendoorn MH, Jaddoe VW, Julvez J, Lahti J, López-Vicente M, Lopez-Espinosa MJ, Manz J, Mileva-Seitz VR, Perola M, Pesonen AK, Rivadeneira F, Salo PP, Shahand S, Schulz H, Standl M, Thiering E, Timpson NJ, Torrent M, Uitterlinden AG, Smith GD, Estarlich M, Heinrich J, Räikkönen K, Vrijkotte TG, Tiemeier H, Sunyer J. Heritability and Genome-Wide Association Analyses of Sleep Duration in Children: The EAGLE Consortium. Sleep. 2016 Oct 1;39(10):1859-1869.