Genetic Link Found for Physical and Psychological Disorders

Results of a series of genome-wide association studies have indicated that insomnia is at least partially hereditary and that it is linked to physical and psychological disorders such as depression and type II diabetes.

Based on earlier genomic studies that had demonstrated the heritability of insomnia, investigators at the University of California, San Diego (USA) conducted genome-wide association studies (GWAS) on DNA samples obtained from more than 33,000 soldiers participating in the Army Study to Assess Risk and Resilience in Servicemembers (STARRS). For this study, GWAS were carried out separately for each ancestral group (EUR, AFR, LAT).

Results published in the March 8, 2018, online edition of the journal Molecular Psychiatry revealed that heritability (SNP-based) for lifetime insomnia disorder was significant. Genetic contributions to insomnia disorder in STARRS were significantly positively correlated with major depressive disorder and type II diabetes, and negatively with morningness chronotype and subjective wellbeing.

In addition, the study identified a genome-wide significant locus on chromosome seven and a genome-wide significant gene-based association in the EUR group on chromosome nine.

"Several of these variants rest comfortably among locations and pathways already known to be related to sleep and circadian rhythms," said senior author Dr. Murray Stein, professor of psychiatry, family medicine, and public health at the University of California, San Diego. "Such insomnia associated loci may contribute to the genetic risk underlying a range of health conditions including psychiatric disorders and metabolic disease. The genetic correlation between insomnia disorder and other psychiatric disorders, such as major depression, and physical disorders such as type II diabetes suggests a shared genetic diathesis for these commonly co-occurring phenotypes. A better understanding of the molecular bases for insomnia will be critical for the development of new treatments."

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