BRCA1 and breast cancer: Furthermore, since 5mTHF is involved in the supply of methyl groups tothe remethylation cycle in which DNA is a terminal acceptor, FA may alter BC risk throughaltered epigenetic regulation of tumour suppressor genes as BC can involve hypermethylation ofP16INK4a, BRCA1, BRCA2, oestrogen receptor (ER)-α, retinoic acid receptor-β2, APC, and RASSF1Apromoters leading to lower transcription and to impaired DNA repair(19–21).