Tooth agenesis in Thai population: prevalence, characteristics and its genetic variant in a Thai family
Authors:   , Kanchanasevee Charinya 
Published: September 2023

Objectives: To assess the prevalence and characteristics of tooth agenesis in Thai population and to identify the genetic variants in a family affected with tooth agenesis.

Methods: Panoramic radiographs in a random sample of Thai patients from 15 to 20 years of age which were taken in 2017 at the Faculty of Dentistry, Chulalongkorn University. Demographic data (age and sex) and dental characteristics of the patients were recorded. A chi-square test was used to determine the differences in the prevalence of tooth agenesis between sexes, maxillary-mandibular teeth, left-right sides, and numbers of missing teeth. Three mL of blood samples were collected for DNA extraction and subjected for mutation analyses.

Results: The overall prevalence of tooth agenesis, excluding the third molars, was 9.23% or 101 out of 1090 patients. The prevalence in females (9.95%) was higher than males (8.23%). According to tooth type, the most common missing tooth was the mandibular second premolars (25.00%; n=55), followed by mandibular lateral incisors (23.28%; n=51), and maxillary lateral incisors (15.91%; n=35). The single most common missing tooth was the mandibular right lateral incisor (15.00%; n=33), followed by the mandibular right second premolar (12.70%; n=28), mandibular left second premolar (12.27%; n=27), and maxillary right lateral incisor (8.64%, n=19). Of all the 101 patients with tooth agenesis, 43.56% had one missing tooth, 41.58% had two missing teeth, 4.95% had three to four missing teeth, and 5.94% had six or more missing teeth. By location, tooth agenesis was found more often on the right side (54.09%) than on the left side (45.91%), and more in mandibular arch (61.82%) than maxillary arch (38.18%). Mutations in WNT10A are the most frequently found in the unrelated 11 probands affected with tooth agenesis (27.27%, n= 3). In the 3 tooth agenesis individuals, the cases were 9 missing teeth, 8 missing teeth, and 2 missing teeth. The first proband was found to have the heterozygous duplication, c.916_918dupAAC (p.Asn306dup), in WNT10A. The second proband possessed the homozygous missense variant, c.511C>T (p.Arg171Cys), in WNT10A and the heterozygous missense variant, c.413A>T (p.Asn138Ile), in EDARADD. The third proband harbored the heterozygous missense variant, c.511C>T (p.Arg171Cys), in WNT10A.

Conclusions: This study reports the prevalence of congenital missing teeth at 9.23% in Thai population. A single tooth absence is most common and according to types of tooth, the mandibular second premolar is the most frequently missing tooth. We identify 3 probands affected with tooth agenesis who have either homozygous or heterozygous variants in WNT10A. The identified WNT10A variants, c.511C> T (p.Arg171Cys) and c.916_918dupAAC (p.Asn306dup), were also found in the patients’ family members who did not have tooth agenesis. It is therefore possible that these WNT10A variants are incomplete penetrant. The pathogenic and causative roles of WNT10A variants requires molecular studies and recruitment of more patients with tooth agenesis.