OBJECTIVETo investigate the mutation characteristics of paired box homeotic gene 9 (PAX9) and muscle segment homeobox gene 1 (MSX1) of patients with congenital oligodontia.

METHODSClinical manifestations were recorded by taking complete oral examinations in patients with congenital nonsyndromic oligodontia and some of his normal family members. Pedigree information was confirmed by extended interviews and a pedigree was constructed. Inheritance mode and clinical features were analyzed. Assessment of crown width compared to normal value of crown width in Chinese people was based on the registrations and measurements of study cast. Comparison of craniofacial form, malocclusion types and characteristics were conducted via cephalometric analysis by taking lateral cephalometric radiographics. Venous blood samples were collected and DNA was extracted from leukocytes. DNA sequencing and mutation analysis were analyzed in exon 1, 2, 3, 4 of PAX9 and exon 1, 2 of MSX1 coding region by polymerase chain reaction (PCR).

RESULTSThe teeth shape abnormality of the patient was noticed by a measured smaller crown width compared to normal values of crown width in Chinese people. The result of cephalometric analysis indicated no obvious inherited tendency in the proband in terms of facial osseo type and jaw bone pattern. One mutation was found in the proband and his mother in exon 3 of PAX9, the missense mutation G718C causing a conservative change A240P was present. Mutation was not found in MSX1.

CONCLUSIONThese findings suggest that the missense mutation G718C in exon 3 of PAX9 is likely the cause of oligodontia.