Examining heightened sense of incompleteness as a candidate endophenotypic marker for skin picking disorder

Excoriation (skin-picking) disorder (SPD) shares genetic underpinnings with obsessive-compulsive disorder, and the phenomenology of both disorders is characterized by heightened sense of incompleteness or "not just right" experiences. The aim of the study was to examine if a general tendency for heightened sense of incompleteness (trait incompleteness) can serve as an endophenotypic maker of SPD. Individuals with SPD ( n=32) and matched healthy controls (n=42) completed two validated self-report measures of trait incompleteness and rated photographs designed to evoke a sense of incompleteness. Additionally, unaffected first-degree relatives of the SPD group (n=18) and the control group ( n=22) completed the same set of measures. The results showed that scores on all the trait incompleteness measures were significantly higher in the SPD group compared to the control group. However, the relatives of the SPD group did not show elevated scores on the incompleteness measures, compared to the control relatives. These data suggest that even though trait incompleteness is a correlate of SPD diagnosis, it does not co-segregate with SPD in families and is therefore not a promising candidate endophenotype for SPD.