The results of our previous studies established an association between polymorphisms in folate metabolism-related genes (MTHFR 677C>T, 1298A>C, TSER 2R/3R, and TS 1494 0bp/6bpins/del) and increased risk of reproductive diseases, including RPL, premature ovarian failure, and spontaneously aborted embryos in the Korean population [30–34]. Here, MTHFR is linked to primary ovarian failure.