Have you ever spit into a tube and sent it off to 23&Me?
I did. It was a super-cool thing to do! Who knew I was part of “something” I never knew about (including a data breach, but that’s another story).
My parents had always said something to me about us being a combination of German, Irish and English but I wanted to see for myself. And I did. In fact, I received a very interesting analysis about my heritage, which uncovered clues about where my ancestors lived, migrated and thrived.
But beyond the “Where did I come from?” discoveries, I learned that I had mitochondrial DNA.
Mito-what?
Mitochondrial DNA.
Let’s take a Squint.
Not One, But Two Genomes
I had always learned that our chromosomes came from mom and dad. True, humans have 23 pairs of chromosomes—23 from Mom and 23 from Dad—for a total of 46 chromosomes in our nuclear DNA. This is the classic double-helix structure that Watson and Crick discovered. It’s the DNA from both parents, carefully packaged in the nucleus of each cell, and it’s the source of traits like Dad’s dimples or Mom’s beautiful eyes. It’s their DNA, all wrapped up in the cell nucleus, ready to be enjoyed (hopefully!) by us.
But why did I order a DNA test to learn about my genes from mom and dad, only to get information that was only about mom? Was there a milkman involved? (Spoiler: No).
Our Two Genomes: Nuclear and Mitochondrial
Here’s the truth: 23&Me doesn’t analyze your genes from mom and dad. It actually dives into your mitochondrial DNA – the genes from mom (and mom only). You see, we actually have TWO genomes, not just one, and both come with chromosomes we inherit.
Our nuclear genome.
This is the one that gets all the recognition in the textbooks. It’s where our DNA from Mom and Dad comes from. It’s those dimples from Dad and beautiful eyes from Mom we mentioned before. Here resides our 23 pairs of chromosomes that tell our story. It’s Mom and Dad joining together to give us what we know as our “genes.” It’s what we commonly refer to as our “gene pool.” It’s the genome that we typically talk about when we refer to things that “run in the family”.
Our mitochondrial genome.
This is the one that 23&Me is talking about. And it’s fascinating. In fact, the understanding of this genome—and the emergence of mitochondrial medicine—may be the biggest advancement in healthcare to date. It’s the genome that resides in our “powerhouse”. It includes mtDNA (mitochondrial DNA) critical in determining how our electron transport chain (in our mitochondria) manufactures energy for our body to use. These mitochondrial genes can be thought of as “the energy that runs in the family” i.e. our family history of how well our cells produce energy to function and ward off disease. You inherited a copy of your mother’s mtDNA (mitochondrial DNA), who inherited it from her mother, who inherited it from grandma, and so on…
Still Confused? Let’s Break it Down
To put it simply, inside each cell, we have a virally-based set of DNA (nuclear DNA) that control our genes (from Mom and Dad. It’s what you’ve always called “your DNA”. Research has now determined we have “another” genome inside each cell, a bacterial DNA that controls energy flux in tissues. And, it may be even more important than our nuclear DNA! It’s called mtDNA (mitochondrial DNA) and we inherit it from mom only, and it’s directly related to how our cells produce energy.
Powerhouse Rules
But wait, there’s more! How we produce our energy (or don’t, if our powerhouse is broken) is directly related to how well our body functions and whether we get sick with diseases like diabetes, Alzheimer’s, breast cancer, cardiovascular disease, neurodegenerative disease and basically most every illness you know.