Pathological and genetic study on children with HTR

Objectives:Hypoplasia of teeth root (HTR) is a genetic disease with defective teeth root. The aim is to clarify pathological phenotype and genetic backgroud of HTR disease, and to obtain practicable and theoretical results for clinical diagnosis.Methods: We collected three cases of HTR to examined them clinically and pathologically,including their early shedding teeth. Based on clinical diagnosis and pathological manifestation, candidate genes ALPL and EDA were picked up to analyze and screen mutation by PCR-SSCP and DNA sequencing methods.Results: Three HTR patients were separately and preliminarily assessed as a novel hypophosphatasia with HTR phenotype, a typical children hypophosphatasia, a novel syndrome (including Dentinogenesis imperfecta, hypohidrotic ectodermal dysplasia, HTR). Then sequencing of ALPL and EDA indicated that three mutations of R136H and P446G in ALPL, L330P in EDA were separately found. Conclusions: Three HTR patients showed distinct phenotypes including systemic and dental abnormalities, which represented many unique and hitherto undescribed disorders with concomitant HTR disease. The mutation types had not been reported, then were regarded as novel mutations related with HTR phenotype. Changes of genes could increase the susceptibility to HTR disease or be the causative factor. Our discoveries indicate the potential function of ALPL and EDA in teeth root initiation.