PAX9 and tooth agenesis: To date, mutations in AXIN2 (axis inhibition protein 2), EDA (ectodysplasin A), MSX1 (msh homeobox 1), PAX9 (paired box 9) and WNT10A (wingless-type MMTV integration site family, member 10a) have been demonstrated to be associated with non-syndromic tooth agenesis [10–16].