# Exploring the Genetic Basis of Dens Evaginatus Using Whole-Exome Sequencing
## 4 Discussion  
To the best of our knowledge, this study is the first to examine the genetic factors associated with DE using WES and identify the candidate gene variants. In total, five individuals from two families of Japanese and Korean origin were included in the present study. The results of WES analysis revealed new variants in _TLR3_ and _MDC1_, suggesting that these gene variants may be potential genetic factors associated with DE. DE is reported more frequently in Asians, Inuit, Alaskan Natives, and American Indians [13; 14; 15]. The present study showed no significant differences in allele frequency, confirming racial differences in the candidate gene variants. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Subject \({}^{*}\)** & **Sex** & **Dental Arch** & **Dens Evaginatus** & **Inclusion Type** \\ \hline A-1 & Female & Lower & Left and right first premolar, right second premolar & Bilateral \\ A-2 & Female & Lower & Left second premolar & Monolateral \\ B-1 & Male & Lower & Left and right first premolar & Bilateral \\ B-2 & Female & Lower & Left first premolar & Monolateral \\ B-3 & Female & - & - & - \\ \hline \hline \end{tabular}  
* Subjects are identified by family such that A-1 is Patient 1 from Family A.  
\end{table} 
Table 1: Clinical characteristics of patients with dens evaginatus from Families A and B. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Genen** & **GenBank** & **Nucleotide** & **Amino** & \multirow{2}{*}{**Aerial ID**} & \multicolumn{4}{c}{**MAF**} & \multirow{2}{*}{**CADD**} \\
**A-2 \({}^{*}\)** & & & & & **GnomAD** & **1000** & \multirow{2}{*}{**ExAC**} & **(Scaled)** \\
**B-1 \({}^{*}\)** & & & & & **EAS** & **Genomes** & \\ \hline _TLR3_ & NM\_003265 & c.1443C\_G & p.Ser81 Arg & rs751882299 & 0.00003229 & 0 & 0.000008283 & 12.35 & Benign \\  & NM\_003265 & c.2491 delA & p.Lys831 fs & - & 0 & 0 & 0 & - & - \\ _MDC1_ & NM\_014641 & c.3908C\_T & p.Pro13031 eu & rs763250651 & 0 & 0 & 0.00008275 & 17.49 & Damaging \\  & NM\_014641 & c.G1825A & p.Gil601 Lys & rs763540794 & 0 & 0 & 8.98 \(\times\) 10\({}^{-6}\) & 14.83 & Benign \\ \hline \hline \end{tabular}  
* Abbreviations: MAF minor allele frequency; GromAD, Genome Aggregation Database; ExAC, Exome Aggregation Consortium; GromAD EAS, Genome Aggregation Database-East Asian; CADD, Combined Annotation Dependent Depletion; PolyPhen2, Polymorphism Phenotyping v2; del, deletion; fs, frame shift.  
\end{table} 
Table 2: Candidate gene variants found in Families A and B. _TLR3_ encodes a protein that plays an essential role in the innate immune system and is a member of the TLR family [22]. [PERSON] et al. [23] isolated and cultured human dental pulp stem/progenitor cells (DPSCs) from human dental pulp and confirmed the expression of TLR in DPSCs under inflamed and noninflamed conditions. Additionally, _TLR3_ has been reported to be expressed in odontoblasts, which are the first cells to encounter pathogens that enter the dental pulp [24; 25]. Another report confirmed the expression of _TLR3_ in human pulp fibroblasts [26; 27]. _TLR3_ is closely related to odontoblasts and human dental pulp. In particular, odontoblasts are associated with tooth formation, including dentin formation [28]. TLR has been reported to be associated with dental mesenchymal stromal cells (MSCs) [29]. MSCs have immunomodulatory properties and multilineage differentiation potential, and have been found in dental pulp, periodontal ligaments, dental follicles, and gingival tissues [29]. MSCs and TLR regulate each other's activity, and can be involved in tissue regeneration and inflammatory disease progression. MSCs are interrelated with TLR and associated with dental components. Further investigation into the function of TLR may help in understanding tooth development. _TLR3_ is potentially related to tooth formation. The relationship between _TLR3_ and tooth formation needs to be further investigated. _MDC1_ is a gene that encodes the nuclear protein MDC1, which is a part of the DNA damage response [30].