i wnat to understand all the information about this SNP (C667T= c665t=rs1801133). i found several names for this polymorphism. i want to know the cause of choosing the number 667 or 665. i think it is the number of the substitute nucleatide iN mRNA but when i ACCESS TO mRNA for this gene (MTHFR) i can't find neither C nor T IN BOTH 665 or 667