FGFR1 and Cowden syndrome 1: Similar to other researchers analyzing these mutations type occurrence, we have shown that causative variants in the FGFR1, FGFR2, FGFR3, TWIST1, and TCF12 genes account for most common cause of CS (Roscioli et al., 2013; Paumard-Hernandez et al., 2015; Lee et al., 2018; Topa et al., 2020).