MAT1A and neoplasm: Index patient 2 presented three likely pathogenic variants SLC3A1 c.1400T > C, MAT1A c.826dupG, and PTGIS c.824G > A. Breast cancer cells have elevated expression of SLC3A1, which accelerates cysteine uptake and accumulates reduced glutathione and decreases reactive oxygen species in tumor cells [62,63].