Number of X-chromosome genes influences social behavior and vasopressin gene expression in mice.

•Here we show that X-chromosome number modifies social behavior in mice with sex chromosome configurations resembling Turner (45, XO) and Klinefelter syndromes (47, XXY).•After analysis of multiple behaviors we show that animals with only one X-chromosome interact less with others than mice with two X-chromosomes.•Using qRTPCR, we noted that amygdala from female mice with one X-chromosome had higher expression levels of vasopressin (Avp) as compared to mice in the other groups.•Examining plasma from girls with Turner syndrome (45, XO) we detected reduced vasopressin (AVP) concentrations as compared to control patients.