KDF1 and ectodermal dysplasia syndrome: Genetic variants in the Keratinocyte Differentiation Factor 1 (KDF1; MIM 616758) gene have been reported in patients with isolated tooth agenesis15, 16, 17, 18 and Ectodermal dysplasia 12, hypohidrotic hair-tooth-nail type (ECTD12; MIM 617337).19, 20, 21 KDF1 is known to modulate the optimal balance between cell proliferation and differentiation, which is fundamental and critical for organ formation during development as well as for tissue maintenance postnatally.