The main findings of this study were: (1) male schizophrenia patients had better language performance than female patients; (2) the FOXP2 rs10447760 genotype did not show an interaction with sex on cognitive performance in schizophrenia patients; (3) there was a positive correlation between BMI and language performance only in male schizophrenia patients; (4) after stratification by FOXP2 rs10447760 genotype, there was a positive correlation between BMI and language performance only in schizophrenia patients carrying the CC genotype. The gene discussed is FOXP2; the disease is schizophrenia.