Heterozygous mutations in AXIN2 have been shown to cause ectodermal dysplasia (including tooth agenesis, or more specifically, oligodontia), and, in some carriers, colorectal cancer and/or adenomatous polyposis develops.
We analysed this novel AXIN2 mutant, together with two reported AXIN2 mutants [c.1966C>T (p.Arg656Stop) and c.1994delG (p.Leu688Stop)] that cause colorectal cancer with and without oligodontia, to study the effect of the mutant p.His660Tyr on the Wnt/β-catenin signaling pathway and to compare the molecular pathogenesis of different AXIN2 mutants in tooth agenesis and carcinogenesis.
To date, the mutation spectra of non-syndromic form of familial and sporadic tooth agenesis in humans have revealed defects in various such genes that encode transcription factors, MSX1 and PAX9 or genes that code for a protein involved in canonical Wnt signaling (AXIN2), and a transmembrane receptor of fibroblast growth factors (FGFR1).
The finding was reminiscent of a previously described family harboring an AXIN2 mutation which could be shown to segregate with both the tooth agenesis and the predisposition to colon cancer transmitted in this family.
Msx1, Pax9, and Axin2 are involved in non-syndromic hypodontia, while genes such as Shh, Pitx2, Irf6, and p63 are considered to participate in syndromic genetic disorders, which include tooth agenesis.
Using multi-temperature single-stranded conformational polymorphism and sequencing analysis, we identified three novel AXIN2 gene variants: c.956+16A > G, c.1060-17C > T and c.2062C > T. We also observed that individuals carrying the c.956+16G and c.2062T alleles exhibited an increased risk of tooth agenesis.