GRB2 mainly functions in activating Egfr tyrosine kinase and its downstream renin-angiotensin system. GRB2 was also involved in the process of development of T cells and Th cells. Studies have demonstrated that GRB2 was significantly up-regulated in aortic valve tissues form CAVD patients. Here, GRB2 is linked to congenital bilateral aplasia of vas deferens from CFTR mutation.