Genetic complexity underlies clinical heterogeneity: YWTD β-propeller mutations and second-hit modifier mutations in LRP6-related tooth agenesis and ectodermal dysplasia in human - Xinxin Dong; Miao Yu; Zhaoyang Jia; Jinye Bai; Jing Zhang; Shengnan Ling; Limin Guan; Yi Lu; Dong Han; Xiwen Gu (Genes and Diseases)