Interestingly, IVF success has been reported using surgically retrieved sperm from men with CBAVD caused by the most severe class of CFTR mutation (Patrizio et al., 1993; Schlegel et al., 1995), suggesting CFTR is not an absolute requirement for IVF success. The gene discussed is CFTR; the disease is congenital bilateral aplasia of vas deferens from CFTR mutation.