LifeGen Technologies, a Madison company studying the genes associated with aging, will be purchased by Nu Skin Enterprises, of Provo, Utah, for $11.7 million. The letter of intent announced Thursday includes LifeGen?s genetic research, patents and tissue bank and says the transaction is expected to be completed before the end of 2011. UW-Madison School of Medicine professors Richard Weindruch and Tomas Prolla founded LifeGen in 2000.