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Typically, items on a questionnaire gauging personality traits, or symptoms used as indicators of psychiatric disorders such as depression, are combined to obtain a composite score (e.g. sum-score or case-control status). Geneticists subsequently use such composite scores to identify genetic variants that are associated to the trait of interest, using a method called the genome-wide association study (GWAS). However, the items or symptoms underlying a trait may not be caused by the same set of genetic variants.Therefore, we studied 12 individual questionnaire items that are often used as indicators of neuroticism. Neuroticism is a stable personality trait that correlates with psychiatric traits like anxiety, substance abuse, and major depressive disorder. The results indicated that the 12 items are genetically quite different. In addition, we identified two sets of items that are genetically very similar. This suggests that analyzing individual items or symptoms, or genetically homogeneous sets of items or symptoms, may provide additional information compared to using a composite score. In turn, this may help advance our understanding of the biological mechanisms underlying personality traits and psychiatric disorders.