About MTHFR a1298c and c677t

trollo

Senior Member
Messages
149
Likes
30
Location
Italy
Hello, i have a question about these two genes: i read that both these SNPs are named that way because if you have the mthfr 1298 with a C instead of a A then you have the bad mutation and if you have the 677 with a T instead of a C too. But when i look into my Genetic Genie panel they say that i am A1298C homozigous with GG and not with a CC and my C677T is negative with a GG instead of a CC... Why?
 

Hip

Senior Member
Messages
16,546
Likes
36,081
There are two conventions: some studies and sources report SNP mutations on the negative DNA strand, others on the positive strand, which leads to confusion. This is known as orientation.

23andme report on the positive strand for all SNP. But other sources may report on the negative, on the positive, or sometimes a combination of both.

To convert one orientation to the other, you transpose A and T, and you transpose C and G. This is because wherever A appears on one DNA stand, T will be in the corresponding position on the opposite strand. And similarly for C and G.

When you have brain fog, this orientation thing makes understanding your SNPs a lot harder.
 

trollo

Senior Member
Messages
149
Likes
30
Location
Italy
There are two conventions: some studies and sources report SNP mutations on the negative DNA strand, others on the positive strand, which leads to confusion. This is known as orientation.

23andme report on the positive strand for all SNP. But other sources may report on the negative, on the positive, or sometimes a combination of both.

To convert one orientation to the other, you transpose A and T, and you transpose C and G. This is because wherever A appears on one DNA stand, T will be in the corresponding position on the opposite strand. And similarly for C and G.

When you have brain fog, this orientation thing makes understanding your SNPs a lot harder.

that's a very clear response. Thank you