NYT: Britain Set to Approve Technique to Create Babies From 3 People
I am really glad the Brits are moving forward with this technique. It will benefit women with mitochondrial disease and allow them to have children and not pass their disease to them.
Ok, here's the deal with this procedure, in a nutshell: The baby's nuclear DNA will STILL come from TWO sources like everyone else's: from the baby's mother and father. What this procedure does is take an unfertilized egg from a SECOND woman, REMOVE that woman's DNA from the egg, insert the DNA from mom and dad, and then let that newly fertilized egg become a human being. Here's the deal: the donor's egg still has the donor's *mitochondrial* DNA.
So, how many genes are we talking about here? Human mitochondrial DNA contains 14 genes (http://ghr.nlm.nih.gov/mitochondrial-dna/show/Genes). Nuclear DNA on the other hand contains approx 20,000 - 22,000 genes. So the amount of genes from the egg donor is minute, about 0.06% of the total number of genes in the baby. Mitochondrial DNA genes encode proteins that are part of the mitochondria's internal machinery. Mitochondrias are the organelles within our cells that perform what is called cellular respiration: they take glucose (from your food) and oxygen (from your bloodstream) and turn it into the ENERGY your body uses to run itself and into carbon dioxide (which you exhale).
So no, Junior will not have the eyes or the nose or the skin color from the nice lady who donated one of her eggs to Mom.
So why would we do such a thing? This therapy is intended to help women with mitochondrial diseases have children and NOT pass the disease to their children. Mitochondrial diseases, caused by mutations in one or more of those 14 genes, are a pretty bad thing, because basically they impact your cell's ability to produce energy, which in turn impacts your organ's functionality.
Quoting: << Diseases of the mitochondria appear to cause the most damage to cells of the brain, heart, liver, skeletal muscles, kidney and the endocrine and respiratory systems. Depending on which cells are affected, symptoms may include loss of motor control, muscle weakness and pain, gastro-intestinal disorders and swallowing difficulties, poor growth, cardiac disease, liver disease, diabetes, respiratory complications, seizures, visual/hearing problems, lactic acidosis, developmental delays and susceptibility to infection >>
Some people see this as an ethical dilemma. They see it as three people having a baby. This is an understandable objection.
However, we've had three-people babies since 1985 : it's called surrogate pregnancies.
Let's not underestimate the womb's role in the baby's development. It's a LOT, a LOT more than what most people think.
Surrogate mom's hormones turn on/off multiple genes on the embryo and later fetus. Surrogate mom's experiences during pregnancies turn on/off multiple epigenetic switches on the embryo. The substances that surrogate mom is exposed to (from food to drink to smoke to stuff in the environment) has profound effect on the embryo/fetus development. In fact, the sexualization of the brain depends MORE on the exposure to certain concentrations of estrogen or testosterone produced by the mother, at certain specific times, than on the baby's own X/Y chromosomes.
There are actual CELLS from the womb mother inside the embryo's body, and actual cells from the embryo inside the mom. These cells are thought to have impact on each other's immune system. For instance, the woman's immune system may react to a male embryo by attacking it as a foreign invader, while the embryo's body may respond by attacking and down-regulating the mother's immune system.
So an embryo is not just doing its own thing by itself inside some rented space within the woman's womb. The woman's body is BUILDING this embryo, step by step. The embryo's genes provide some of the recipe, but the mother's body is the chef and the cook and alters the recipe at will , sometimes a LOT.
Life, in general, is not a deterministic process. There are lots of underlying stochastic (probabilistic) processes. DNA expression is not a deterministic process, and in a developing embryo a LOT of gene expression is driven by mom: which genes get turned on/off, when, and for how long.
People think of DNA as a blueprint. It's NOT. It's more like a *RECIPE*. Take any long complex recipe. Think of all the things that a chef can alter. She can substitute materials, or use a bit more or a bit less than expected. She can shake or stir with more/less strength, for longer/shorter times. She can use higher or lower temperatures than what the recipe calls for. Some days the chef will be pissed, some days she'll be happier, some days she'll be bored, some days she'll be sick, other days she'll be drunk, and ALL that will reflect on how she prepares whatever food she's making that day.
And sometimes the chef misinterprets things. Sometimes the recipe calls for a ham sandwich, but the chef will make a turkey sandwich instead...