Dental agenesis in this respect is believed to result from altered expression of one or more of these factors during initiation and early morphogenesis of the tooth germ, and the first actors identified were MSX1 and PAX9.
MSX1 and PAX9 have been associated with tooth agenesis in mice and humans, but interestingly for humans, these genes are associated with specific missing teeth.
The findings show that isolated dental agenesis exists as part of a spectrum of syndromes for all the identified genes except PAX9 and that the pattern of dental agenesis can be useful in clinical diagnosis to identify (or narrow) the causative gene mutations.
In order to screen for the eventual genetic cause of dental agenesis in this family we sequenced 4 genes; PAX9, WNT10A, MSX1 and AXIN2 using Sanger sequencing.
CONCLUSIONS; These results bring us to conclude that probably other genes can determine phenotypical patterns of dental agenesis in the families studied, different than the ones described in the mutations of PAX9 and MSX1.
Homozygosity for the PAX9Ala240Pro mutation was studied in a family (proband and her parents), suggesting recessive inheritance with variable expressivity for the dental agenesis found.
The significantly smaller tooth crown dimensions recorded in the affected family members show that the effect of the PAX9 mutation is seen not only in the congenitally missing teeth but also in smaller crown size throughout the dentition.
Missing teeth (hypodontia and oligodontia) are a common developmental abnormality in humans and heterozygous mutations of PAX9 have recently been shown to underlie a number of familial, non-syndromic cases.
MSX1 and PAX9 have been associated with tooth agenesis in mice and humans, but interestingly for humans, these genes are associated with specific missing teeth.
Genetic variations in genes known to be associated with EDs that affect only one derivative of the ectoderm (attenuated phenotype) will be grouped as non-syndromic traits of the causative gene (e.g., non-syndromic hypodontia or missing teeth associated with pathogenic variants of EDA "ectodysplasin").
As the most common form of ectodermal dysplasia (ED), X-linked hypohidrotic ED (XLHED) is characterized by the triad of hypohidrosis, hypotrichosis, and anodontia in male patients.The gene responsible for XLHED is EDA.