People who want to start a family, and who are carriers of a genetically heritable disease, face difficulties. A new technique has been developed that will use DNA from two adults, and a donated egg from a third adult, in order to create a baby. The first “three-parent” baby has been born.
The phrase “three-parent” baby is a misnomer. It’s a simplified way to describe a complex procedure. The purpose is to enable a woman who is a carrier of a debilitating or fatal genetically heritable disease to have a healthy baby.
The process starts with an egg that contains unhealthy mitochondria. The mother’s nuclear material is removed from that egg and kept. Next, a donor (who has healthy mitochondria) donates an egg. The nuclear material from that egg is removed and replaced with the mother’s nuclear material. Sperm is required for that egg to be fertilized.
Genealogists need not alter their family trees to include three parents for one baby born from this technique. The baby will still have two parents – the mother whose nuclear material was placed into a donated egg, and the father who supplied the sperm. The third person does not contribute any genetic material to the baby.
In April of 2016, doctors led by John Zhang, from the New Hope Fertility Center in New York, decided to attempt this controversial mitochondrial transfer technique in the hopes that it would give a couple a healthy baby.
The mother in that couple carried genes for Leigh syndrome (which is also called Leigh’s disease.) It is a progressive neurometabolic disorder that starts in infancy. The child appears normal at birth, but loses the basic skills such as sucking, head control, walking, and talking. The disease can lead to heart, kidney, vision, and breathing complications. There is no cure for Leigh disease.
The woman in the couple did not have a pregnancy until ten years after they got married. She experienced four miscarriages. The couple then had a baby girl who died at the age of 6, and a second baby who lived for eight months.
The doctors led by John Zhang preformed the “three-parent” baby technique in Mexico – and a healthy baby boy was born. This is controversial because Mexico has less stringent regulation than some other countries. It is unclear how many attempts were made before a healthy baby was born. There are questions that remain unanswered regarding what follow up treatment the baby should have.
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