Pre-eruptive Coronal Resorptions as a Clinical Feature of FAM83H-Related Amelogenesis Imperfecta: Insights from Two Brazilian Families.

Amelogenesis Imperfecta (AI) is a group of rare hereditary conditions characterized by quantitative and/or qualitative enamel defects affecting both primary and permanent dentitions. Among the more than 70 genes associated with AI, FAM83H is the only gene known to cause autosomal dominant hypocalcified AI (ADHCAI). Recent studies have shown that causative variants in FAM83H disrupt amelogenesis and may also affect dental follicle cells, potentially leading to tooth impaction in ADHCAI patients. Here, we report two unrelated Brazilian patients with ADHCAI who present a distinctive and severe phenotype characterized by delayed eruption, multiple impacted teeth, and pre-eruptive crown resorptions (PECR). Longitudinal radiographic analysis revealed multiple unerupted teeth with progressive PECR. Using whole-exome sequencing, we identified two nonsense heterozygous FAM83H causative variants (c.1055 C > A, p.Ser352*; c.1379G > A, p.Trp460*). Our findings represent the first report of FAM83H-related ADHCAI in Brazilian families and expand both the phenotypic spectrum and clinical severity associated with this gene. The presence of widespread PECR and adjacent bone alterations suggests that FAM83H dysfunction may affect not only enamel formation but also tooth eruption pathways and local tooth-bone interactions. This study highlights the importance of early diagnosis, individualized radiographic follow-up, and genetic testing to guide counselling and clinical management of affected individuals.