{{Genotype
|rsid=1801131
|allele1=C
|allele2=C
|magnitude=2.1
|repute=Good
}}
MTHFR rs1801131 is involved in converting 5-methylfolate (5MTHF) to tetrahydrofolate (THF). Unlike MTHFR C677T, this mutation does not lead to elevated homocysteine levels.