“…Based on the number of missing teeth (not including third molars), tooth agenesis can be classified as hypodontia (less than 6 missing teeth), oligodontia (6 or more missing teeth), and anodontia (all teeth missing) [ 3 , 4 ]. To date, NSH has been reported to be associated with mutations in ectodysplasin-A ( EDA ), ectodysplasin-A receptor ( EDAR ), EDAR-associated death domain ( EDARADD ), wnt family member 10A ( WNT10A ), wnt family member 10B ( WNT10B ), paired box 9 ( PAX9 ), msh homeobox 1 ( MSX1 ), axis inhibition protein 2 ( AXIN2 ), and inhibitor of nuclear factor kappa B kinase regulatory subunit gamma ( IKBKG ) [ 5 – 7 ]. Among these, EDA mutations could cause SH, which appears as an X-linked hypohidrotic ectodermal dysplasia (XLHED) clinical feature, and they have also been linked to isolated tooth agenesis, most likely due to complete or partial disruption of the EDA signalling pathway [ 8 , 9 ].…”