A just-discovered genetic mutation that causes one type of male infertility may help in the creation a birth control pill for men. The mutation occurs on a protein in sperm called PLC zeta, and it makes sperm defective. The European researchers studied the sperm of nine men at a fertility clinic. The mutation disabled the protein from fertilizing or “activating” the female’s egg. The team suggests that developing a drug that inhibits the PLC zeta protein could be used as a male contraceptive.