Genetic etiology and dental pulp cell deficiency of hypophosphatasia.

[dentin dysplasia]

Hypophosphatasia is caused by mutations of the tissue-non-specific alkaline phosphatase (TNSALP ) gene with deficiency of dentin structure . The aim of this study was to examine whether TNSALP mutation in dental pulp cells contributes to dentin dysplasia in hypophosphatasia . Mutation analysis showed that compound heterozygous mutations of TNSALP were identified in three hypophosphatasia patients , including 3 novel mutation sites . Exfoliated teeth from the patients showed abnormal dentin mineralization and loss of cementum , as assessed by ground sections and scanning electron microscope analysis . Dental pulp cells isolated from one of the patients showed a significantly reduced TNSALP activity and mineralization capacity when compared with those in dental pulp cells from the unaffected individuals . Our results suggested that dentin dysplasia in hypophosphatasia may be associated with the decreased mineralization ability of dental pulp cells .