Abnormal social behaviors in Dlgap2−/−mice. (A-B) Social approach and novelty tests, n = 8 per genotype. Dlgap2−/−mice had an intact social preference, spending a longer time spent in the social region, and intact social novelty performance. (C-E) Resident–intruder task, n =7 Dlgap2+/+ (WT) and 8 Dlgap2−/− (KO) mice. Dlgap2−/−mice had a shorter attack latency, and exhibited more prolonged and increased frequency of aggressive behaviors. (F) Dlgap2−/−mice had a higher probability of winning in the tube test, n = 8 pairs of mice. Data are presented as mean ± standard error of the mean. *P < 0.05, **P < 0.01 and ***P < 0.001 from two-tailed t-tests for (A), (B) and (E), Mann–Whitney U test for (C) and (D), and chi-squared test for (F). KO, knockout; WT, wild type.