The genes in mitochondria, which are the powerhouses in human cells, can cause fatal inherited disease. But replacing the bad genes may cause other health problems.
Getty Images/Science Photo Library
Cleveland Clinic surgeons in February transplanted a uterus from a deceased donor into 26-year-old Lindsey McFarland, who was born without one. Though the experimental surgery was initially thought successful, a raging infection forced removal of the organ within weeks.
Frozen sperm straws and embryos are stored in liquid nitrogen, in a process known as cryopreservation. One question confronting the courts: Should embryos such as these be treated as property, or as children subject to custody action?
Veronique Burger/Science Source
Along with sperm, the in vitro procedure adds fresh mitochondria extracted from less mature cells in the same woman's ovaries. The hope is to revitalize older eggs with these extra "batteries." But the FDA still wants proof that the technique works and is safe.
Chris Nickels for NPR