[Clinical features and genetic mutation analysis of the hereditary dentin dysplasia type Ⅰ family]

Dentin dysplasia type Ⅰ (DD-Ⅰ) is a rare autosomal dominant hereditary disorder characterized by abnormal dentin development. Its primary clinical features include markedly shortened tooth roots and pulp chamber closure. The causative genes and molecular mechanisms have not been fully elucidated yet. This study reports a DD-Ⅰ family comprising four affected individuals. Pathogenic mutations were identified and assessed using whole-exome sequencing combined with co-inheritance analysis and bioinformatics methods. Results revealed that the proband exhibited typical DD-Ⅰ clinical phenotypes, including root shortening, pulp chamber closure, and alveolar bone resorption. A highly conserved missense mutation c.353C>A (p.P118Q) in the SSUH2 gene was detected within the family. Bioinforma-tics prediction indicated this mutation significantly alters protein secondary structure and three-dimensional conformation, classified as "likely harmful." Combining bioinformatics analysis with clinical phenotype correlation further validated the causal relationship between this mutation and DD-Ⅰ, providing supplementary experimental evidence for the pathogenicity of the p.P118Q mutation.