A large-scale international study has investigated the influence of genes on sleep behavior. Within the framework of this collaboration, scientists of Helmholtz Zentrum München report in ‘Nature Genetics’ that several genes play an important role in sleep disorders – including one that is also associated with the restless legs syndrome (RLS).
More than 100,000 study participants
Previous research has shown that stress during the day is not the only cause for not being able to sleep at night. Genetic causes also contribute to the pathogenesis of chronic insomnia. In women, the proportion of genetic causes (i.e., the heritability) appears to be 60 percent; in men it is around 40 percent. To find out which genes are specifically responsible for insomnia, scientists led by Oexle, together with colleagues from the Netherlands and Iceland, have undertaken a large-scale study.
They performed a genome-wide association study (GWAS) and a genome-wide gene association study (GWGAS) of 113,006 subjects of the UK Biobank and looked for common variants among those who suffered from sleep disorders. The authors found seven genes and three other genes in the genome. They then included another sample of 7,565 subjects in their analysis which allowed to confirm a total of five genomic regions as relevant.
Association with the restless legs syndrome?
One gene turned out to be particularly interesting. “Our top candidate MEIS1 most likely plays a key role in insomnia,” said Professor Juliane Winkelmann, director of the Institute of Neurogenomics and one of the authors of the study. “This is also interesting because the gene MEIS1 is also associated with the restless legs syndrome, which we have been investigating for years.” **
Konrad Oexle looks to the future: “Our study can serve as a concrete starting point for new molecular biology studies on the development and treatment of insomnia.” In the long term, the scientists want to open up new therapeutic options for the growing proportion of the population suffering from sleep disorders. In their opinion, too few studies have been carried out on the causes of the disease, especially in view of the accompanying and secondary diseases. Oexle: “The problem is too often attributed to the psychological state of those affected, but our study shows that it is also genetic.”
* Other studies report even significantly higher numbers of up to 22 percent (see journal publication).
** Juliane Winkelmann has been investigating RLS for a long time. In her further research, she will seek to determine to what extent the causes of restless legs syndrome and the restlessness of insomnia coincide.
Furthermore, the scientists identified genetic correlations with other mental symptoms such as anxiety states or depression. In addition to Konrad Oexle, Danielle Posthuma and Eus van Somerern from the Netherlands co-directed the study. The data came from the UK Biobank. This large-scale project collects health data from 500,000 volunteer participants in the United Kingdom to improve the prevention, diagnosis and treatment of numerous diseases. These include, for example, diabetes, dementia, cancer and other common diseases.
Hammerschlag, A.R. et al. (2017): Genome-wide association analysis of insomnia complaints identifies risk genes and genetic overlap with psychiatric and metabolic traits. Nature Genetics, DOI: 10.1038/ng.3888
As German Research Center for Environmental Health, Helmholtz Zentrum München pursues the goal of developing personalized medical approaches for the prevention and therapy of major common diseases such as diabetes mellitus and lung diseases. To achieve this, it investigates the interaction of genetics, environmental factors and lifestyle. The Helmholtz Zentrum München has about 2,300 staff members and is headquartered in Neuherberg in the north of Munich. Helmholtz Zentrum München is a member of the Helmholtz Association, a community of 18 scientific-technical and medical-biological research centers with a total of about 37,000 staff members.