 MSX1 is one of the strongest candidate genes for specific forms of tooth agenesis, mutations in this gene was detected only in some affected individuals.Genes expressed in the early dental epithelium in mice such as Bmp4, Bmp7, Dlx2, Dlx5, Fgf1, Fgf2, Fgf4, Fgf8, Lef1, Gli2, and Gli3 are also potential candidates.Based on existing evidence, it seems possible that both hypodontia and oligodontia are heterogeneous traits, caused by several independent defective genes, which act along or in combination with other genes and lead to specific phenotypes.