LRP6 and tooth agenesis: The proband of Family 2, who carried three LRP6 variants and WNT10A p.(Gly213Ser) mutation, exhibited a much more severe disease phenotype, including severe oligodontia, perioral dryness, and hyperpigmentation, than that of his father, who had only the LRP6 variants and hypodontia, suggesting a potential mutational synergism on disease expressivity.