Mutations on CD40L gene are associated with X-Linked Hyper-IgM syndrome; a family genetic disorder characterized by an increase of IgM level and a decrease of IgG and IgA [30]; other mutations and/or altered expression of CD40L, common γ chain, FOXP3 (forkhead box P3) among other genes encoded on the × chromosome, are known to be cause of immune disorders such as X-SCID and IPEX dramatically manifested in men, while females can compensate or reduce severity of the symptoms due to the second × chromosome. This evidence concerns the gene CD40LG and hereditary disease.