Archiver > GENEALOGY-DNA > 2010-03 > 1269437349

Subject: Re: [DNA] Re : Usefulness of SNP tests
Date: Wed, 24 Mar 2010 09:30:42 EDT

The locations of PSORS1 and PSORS2 are on chromosomes 6 and 17, so an mtDNA
test would be irrelevant. (Note I had typos in my prior message, in case
you are Googling.)

I have not seen any Family Finder results, so I'm not sure if they would
be similar to the Family Inheritance diagrams at 23andMe for sibling
relationships. The FI diagram will show segments that are completely identical,
half-identical, or not identical. Thomas Krahn at FTDNA has expressed
reservations about the utility of this type of test for full vs half-sibling
relationships, so FTDNA may not implement a similar scheme.

Anyway, the most that 23andMe's FI could tell you is whether you could rule
out a region because it is completely identical (you and your sibling
received the same segments from your father AND your mother). This would be a
study similar to the one I described for cousins in my recent 'Satiable
Curiosity column "Mix and Match: DNA Stories From an Ancestor." Cousins are
actually more informative for this kind of study than siblings, who share a lot of
DNA that is irrelevant to the trait.

Actually, it would be a bit more complicated. There are 12 PSORS regions
identified to date, and penetrance is not 100% (that is, you might have the
mutation, but there are other genetic or environmental factors at work, and
you don't exhibit the symptoms).

Ann Turner

In a message dated 3/24/2010 3:41:26 AM Pacific Daylight Time,

> Hi Ann,
> Thanks for sharing that article. I have psoriasis in my family. My
> father and older sister used to get it on their eyebrows and elbows and knees
> but my younger sister has it all over her body and gets injections. I have
> been lucky and only get hives. My mother and brother get eczema. My
> question is that I have had mtDNA Full Sequence and have sent for the
> Familyfinder test at FTdna would one of these tests show if I have the PSOR1 &PSOR2
> regions?
> Thanks,
> Nancy

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