Research progress on selective tooth agenesis caused by LRP6 gene mutation

Selective tooth agenesis (STA) is an abnormal number of teeth due to genetic factors or the environment and is most commonly observed for permanent teeth. LRP6 is one of the common causative genes of STA and is inherited by an autosomal dominant mechanism, leading to non-syndrome tooth agenesis (NSTA) or syndrome tooth agenesis (STA). NSTA is only involved in tooth number and appearance abnormalities, whereas STA caused by LRP6 gene mutation results abnormal ear development, oral-facial clefting, sparse hair and hypohidrosis. In this paper, we review the phenotype and gene mutation traits of selective STA caused by LRP6 gene mutation identified in recent years and describe 38 patients with tooth agenesis from 24 mutation sites of LRP6 gene. We analyzed the percentage of missing teeth and found that the lateral incisor in the maxilla and the second premolar in the maxilla and mandible were most commonly lost, whereas all central incisors in the maxilla remained. LRP6 gene plays a major role in tooth development via the WNT/β-catenin signaling pathway, and LRP6 gene mutation can lead to a series of abnormal manifestations due to the disruption of the signaling pathway. The literature showed that LRP6 gene mutations occurred mostly at the E1 or E2 subdomain, meaning that STA due to the mutants extracellularly disturbed the WNT/β-catenin signaling pathway. However, mature treatments for selective congenital tooth loss are lacking.