Association Of EXT And FGFR3 Genes With Condylar Osteochondroma

Objective:To investigate the association of mutations in the EXT and FGFR3 genes with osteochondroma of the condyle and their mechanism of action in condylar osteochondroma,and to provide a basis for clinical treatment of condyle osteochondroma.Methods:Osteochondroma lesion tissues were collected from inpatients of the Department of Oral and Maxillofacial Surgery of the Affiliated Stomatology Hospital of Kunming Medical University after surgical resection.Clinical manifestations and imaging features were analyzed,etc.Peripheral blood was used for gene whole-exome detection of EXT1 and FGFR3 gene mutations.Immunohistochemical methods were used to detect the expression of the expression of EXT1 and FGFR3 proteins in the tissues.Results:A total of 25 cases of condylar osteochondroma.The male-to-female ratio is 1:1.27,the age is 11-65 years,with an average age of 38.8years.The ratio of left and right sides is 1.78:1.96%（24/25）of patients had facial asymmetry,and 40%（10/25）had restricted opening.One patient also had bilateral styloid process elongation.Four patients who underwent the whole exome test all had FGFR3 gene mutation,and three had common site mutations:Chr4:1805571.NM₀00142.4:exon12:c.1547A>G.Two patients had EXT1 gene mutations and located at the same site:Chr8:117807339.NM₀00127.2:exon9:c,1761G>A.However,immunohistoche-mical staining of 25 patients showed that EXT1 was expressed in 17 cases of condylar osteochondroma,while FGFR3 was expressed in only 5 cases.Conclusions:The results of this study show that condylar osteochondroma is not only related to EXT1 gene mutations but may also related to FGFR3 gene mutations.However,FGFR3 gene mutation was detected in 4 cases of solitary osteochondroma,FGFR3 protein expression was negative.The results of whole exon detection and immunohistochemical staining are inconsistent,the specifically related mechanisms need to be further studied and confirmed.