ANO5 p.I616F variant drives florid cemento-osseous dysplasia by disrupting transmembrane domain structure

To date, genetic studies on florid cemento-osseous dysplasia (FCOD) remain limited. This study aimed to elucidate the clinical features and genetic basis of FCOD in Chinese populations, with particular emphasis on identifying pathogenic ANO5 variants and their mechanistic contributions to disease development. Clinical data from 17 FCOD patients diagnosed between May 2015 and December 2024 at Kunming Medical University Affiliated Stomatological Hospital were retrospectively analyzed. Whole-exome sequencing was performed on a familial cohort (8 individuals). Identified variants were validated using Sanger sequencing. Pathogenicity was predicted via SIFT, PolyPhen-2, and MutationTaster, while protein structural alterations were modeled with AlphaFold 2. Histological assessment included H&E staining, Masson trichrome, RUNX2 immunohistochemistry, and TRAP staining to quantify osteoclastic activity. Among the 17 FCOD patients included in this study, 10 (58.8%) were female, with a mean age of 47.4 ± 13.2 years. Genetic analysis identified Anoctamin 5 (ANO5) variants in five cases, including a novel variant (p.I616F). Pedigree analysis confirmed that p.I616F was a heterozygous variant, and bioinformatics prediction indicated its likely pathogenicity. Structural modeling further demonstrated that this variant disrupted the α-helix of ANO5 and altered the catalytic site’s conformation. Additionally, histological evaluation revealed significantly elevated RUNX2 expression and increased osteoclast activity in the jawbone tissues of FCOD patients. This study provides the first evidence that ANO5 variants (particularly p.I616F) may represent key genetic factors contributing to FCOD development in the Chinese population. The mutation likely disrupts the α-helical structure of ANO5 protein, impairing its catalytic function and potentially dysregulating bone remodeling processes in FCOD pathogenesis.