A new procedure designed to eliminate some hereditary diseases results in children with DNA from a mother, father and a third donor -- the so-called "three-parent child." While some scientists laud the advance for its ability to prevent certain disorders, others caution that that it might pave the way for ethically dubious forms of genetic manipulation. Our guests: Dr. David Valle, director of the Johns Hopkins McKusick-Nathans Institute of Genetic Medicine; and bioethicist Debra Mathews, assistant director for Science Programs at the Johns Hopkins Berman Institute of Bioethics. Guest host Nikki Gamer