PTCH gene altered in dentigerous cysts

Motivated by the evidence that odontogenic keratocysts are associated with genetic alterations, we examined the possibility that development of other odontogenic cysts can be attributed to gene malfunctioning, in particular t o the PTCH gene. Cyst epithelium was examined for polymorphism on chromosom e 9q22.3, the region that contains the PTCH gene. Loss of heterozygosity (L OH) for the D9S287 marker and/or D9S180 marker was observed in about 50% of dentigerous cysts, whereas radicular cysts gave no indication of lesions i n the PTCH region. As a more direct argument for PTCH involvement in cystic growth, we report evidence of PTCH expression in dentigerous cyst lining, which indicates malfunctioning of the relevant signaling pathway. While we found no reason to believe that PTCH should be associated with radicular cy sts, other genes may be implicated in their development. We performed immun ohistochemical comparisons of keratocysts, dentigerous and radicular cysts for the nonmetastatic marker Nm23. A graded response placed radicular cysts in between the other two types, suggesting a similar neoplastic character for their epithelial proliferation.