Considering the influence of various mutations in the coding region of the MSX1 gene homeodomain, it is important to note that functional analysis of five missense mutations (Met61Lys, Ala194Val, Arg196Pro, Ala219Thr, and Ala221Glu) associated with hypodontia revealed that previously known molecular mechanisms could not fully explain the significance of these amino acid substitutions in tooth agenesis [22]. This evidence concerns the gene MSX1 and tooth agenesis.