The study by Hill et al. (8) in this issue focused on cognitive endophenotypes. The Brief Assessment of Cognition in Schizophrenia (BACS) was used to evaluate memory, working memory, motor speed, attention, executive functions, and verbal fluency. The study group comprised 293 individuals with schizophrenia and 316 of their first-degree relatives, 227 with psychotic bipolar disorder and 259 of their relatives, 165 with schizoaffective disorder and 197 of their relatives, and 295 healthy comparison individuals. Cognitive task performance was compromised in patients and their relatives. No diagnosis-related qualitative differences were found in the composite or domain-specific BACS scores. The degree of impairment was influenced by psychopathology; more prominent affective symptoms and less persistent psychotic features were associated with less cognitive impairment. Cognitive impairment was associated with subthreshold psychoticism in relatives, as captured by the presence of cluster A personality disorders. Symptomatic expression and cognitive dysfunction were closely linked only in families with bipolar disorder. Cognitive dysfunction segregated with subthreshold psychoticism in the relatives of bipolar patients, while in the relatives of patients with schizophrenia it was present independent of symptoms.