Genome-wide association study of social isolation in 63,497 Japanese individuals from the general population

Social isolation, characterized by a lack of social connections with family, friends, and others, is associated with adverse health outcomes. However, the genetic contribution to the susceptibility to social isolation remains unclear. This study aimed to identify genetic loci associated with social isolation using the Lubben Social Network Scale (LSNS-6) in a Japanese population. The Tohoku Medical Megabank Community-Based Cohort Study was conducted between 2013 and 2016. The participants were genotyped using the Affymetrix Axiom Japonica Array. The LSNS-6 was used to assess familial and friend ties through six questions and social isolation statuses were defined using the total scale, family subscale, and friend subscale. Genome-wide association studies (GWASs) were conducted using a generalized linear mixed model, adjusting for age, sex, 10 genetic principal components and batch effects. In total, 63,497 participants who completed genotyping and the LSNS-6 were included. The mean age was 59.4 ± 11.9 years, and 41,126 (64.8%) were female. Significant genetic loci were identified in GWASs for the total scale (rs10736933 near ACADSB and HMX3) and friend subscale of LSNS-6 (rs1778366 near LINC02315 and LRFN5). This study provides the first genome-wide evidence of social isolation in the Japanese population, suggesting associations with ACADSB, HMX3, LINC02315, and LRFN5. These findings could enable personalized prevention and intervention for social isolation and related psychiatric disorders.