Headlines on Feb. 3 announced the British Parliament’s approval of “ three-parent babies” in the United Kingdom as a prevention of mitochondrial disease, which claims the lives of very young children born with the ailment, which causes loss of muscle tone, cardiac issues and other problems.
To be accurate, the approval was voted for in the House of Commons and still needs to go to the House of Lords before becoming law.
How is this connected to the mitochondrial DNA line that many genealogists like to trace in their families?
I’ve often referred to mitochondrial DNA as that which comes from the “mother’s mother’s mother’s mother’s mother … and so on.” Picturing this might help.
The day after Christmas I excitedly told my husband, “We got a mitochondrial DNA Christmas card from the Mackenzies!”
Actually, this Christmas card from Tony’s in-laws in Minnesota contained a few pages with several pictures of the family over the past year, including my Saucier grandchildren out there. But the cover picture was definitely a mitochondrial DNA photograph.
The oldest generation was represented by Lee (Wilcox) Barthel, beloved great-grandmother and “Maga” to us youngsters in the family. Her daughter is grandmother Julie (Powell) Mackenzie, and Julie’s daughters are Heather (Taylor) Saucier and Kelsey Mackenzie. Heather’s daughter (my granddaughter) is Arabelle Georgette Saucier, born last summer in Minnesota.
If you start with Arabelle, her mitochondrial DNA line goes back through Heather and Julie to Lee and then her mother Rose, and so on.
Anyways, mitochondria is genetic material that surrounds the nucleus of the egg, which explains why the disease follows the maternal line. One news story I saw compared mitochondria, which convert food in the cells to energy, as the batteries of each cell of the body.
The method of correcting for the problem of mitochondrial disease involves one of two approaches, according to scientists.
One approach would take the nucleus from a mother’s egg that has the defective mitochondria and use it to replace the nucleus in a donor egg from another woman, then fertilize that egg with the father’s sperm through IVF, or in vitro fertilization.
Doing so would not change the hair color, eye color or appearance of the baby. The child would, however, pass on genes containing material from the mom, the dad and the mitochondria of the donor.
A different approach would take an embryo fertilized by the parents which contains defective mitochondrial DNA of the mother. Scientists would remove the pronuclei from the embryo and and use it to replace the pronuclei in a donated embryo, which has normal mitochondrial DNA. The child would get most of its genetic material from the parents, who supplied the pronuclei, plus a bit from the donated mitochondria.
The media, in an effort to help everyone understand what is being proposed, in many cases simply says the baby has “three parents.”
But the resulting embryo, presuming it gestated for nine months and resulted in birth, would result in a child that technically would have only 1/10 of 1 percent of the donor’s genetic material through the donated mitochondria. So, it is calculated, this IVF procedure would more accurately be described as resulting in a child with “2.001 parents,” not three.
Years ago, when the first child by IVF in the world was born in England, babies born from this method were often called “ test tube babies.”
In 1981, the first child in the United States born by IVF was to a mom who had lost both fallopian tubes to ectopic pregnancies, which occurs when the fertilized egg lodges in the fallopian tube and grows there rather than in the uterus.
The parents of that baby, who was born in Virginia, were both University of Maine graduates, who attended school when I did, though I don’t believe I knew them.
Both boys and girls inherit mitochondrial DNA, but only girls can pass it on, which is why we call the mitochondrial line the “maternal line.” So while I do have granddaughters, they do not have my mitochondrial DNA, because both of my children are boys.
As was depicted in the Christmas card with the photo showing Arabelle, my granddaughters have their mom’s mitochondrial DNA.
For information on researching family history in Maine, see Genealogy Resources under Family Ties at bangordailynews.com/browse/family-ties. Send genealogy queries to Family Ties, Bangor Daily News, P.O. Box 1329, Bangor 04402, or email familyti@bangordailynews.com.