mitochondrial DNA

[bickerer]

I've googled until my fingertips fell off, and I'm no closer to an answer than yesterday. This question is prompted by an old rerun of Law & Order. The Pathologist linked blood from a crime scene to a suspect through Mitochondrial DNA (or so she said). Is this possible? Was she linking it through the mutations in the DNA? Wouldn't Mitochondrial DNA just link to everyone? I pulled a copy of Power, Sex, Suicide off the shelf here at the store (as well as the frantic typing into search engines), but my head exploded around page 15, and as I'm just a simple bookseller, I'm looking for an answer that a 16 year old would understand, if possible. But I'm not adverse to pie charts and graphs...........
Thank you smart people.

 

[Mr.D]

Simple answer: Mitochondrial DNA is passed from mother to child.^*
So in that L&O episode, the blood could have come from the suspect, the suspect's mother, or the suspect's full siblings, half-siblings (by a common mother) or children (if the suspect is female) if any. Presumably there was dialogue to explain how they distinguished the suspect from the others.





^* Mitochondrial DNA does mutate as it passes from generation to generation, but the rate is fairly slow.

 

[casebro]

mtDNA is used a lot. Try Google for <forensics mtDNA>

 

[jasonpatterson]

So in that L&O episode, the blood could have come from the suspect, the suspect's mother, or the suspect's full siblings, half-siblings (by a common mother) or children (if the suspect is female) if any. Presumably there was dialogue to explain how they distinguished the suspect from the others.

Also any cousins if the maternal grandmother had more than one daughter, second cousins if maternal great grandmother had multiple daughters and they had daughters, etc. I don't know how far back you'd have to go to get meaningful differences, but there ya go. There could be a substantial number of people with the same mtDNA as any particular individual.

 

[Tiktaalik]

If you have a further interest in mitochondrial DNA, try "The Seven Daughters of Eve"...re: tracing genetic ancestry.

 

[dudalb]

Simple answer: Mitochondrial DNA is passed from mother to child.^*
So in that L&O episode, the blood could have come from the suspect, the suspect's mother, or the suspect's full siblings, half-siblings (by a common mother) or children (if the suspect is female) if any. Presumably there was dialogue to explain how they distinguished the suspect from the others.





^* Mitochondrial DNA does mutate as it passes from generation to generation, but the rate is fairly slow.

Unless the readings are off the scale.......

 

[McHrozni]

It's possible to get a match with mtDNA to approximately 1 in 1000, IIRC. Standard testing with genomic DNA can match an individual to approximately (and up to) 1 in 10,000,000,000,000.
Mitochondrial DNA is therefore only used if the quantity of useful genomic DNA is too small to produce a meaningful profile. It is also inherited via maternal line (in about 99,99% of individuals), so you can't distingush a mother from a son or daughter via mtDNA alone.

It can be very useful in special cases.

McHrozni