The Clinical Analysis And PAX9/MSX1Genetic Testing Of Patients With Non-syndromic Oligdotia

Objective:To evaluate Oral and maxillofacial growthing statues of29non-syndromic hypodontia cases (include17sporadic cases and12probands from10families with non-syndromic hypodontia) through clinical examination; to detect the genetic defect of PAX9and MSX1genes in the29cases and to obtain the probable pathogenic causes of the disease’s occurrence.Method:We analyzed the developmental conditions, craniofacial morphology and malocclusion of29cases by common clinical examinations(include oral clinical examination, model analysis and cephalometrics). And by using PCR and DNA sequencing to screen PAX9and MSX1genes in the29cases we detected the mutations of these genes and obtained the genetical characteristics of the disease’s occurrence, and analyzed the corresponding relation between clinical phenotype and gene type.Results:1. The results of clinical examination:(1)In the29cases contains10males (34.5%) and19females (65.5%); patients’ages range from24-27; Han Chinese(28cases,96.6%) and Hunan patients(17cases,58.6%) are in the majority.(2)1patient (3.4%) is of multiple missing teeth,28patients (97.8%) is of few number missing teeth; the probability for the position of missing teeth are:lower lateral incisor(21.7%)> lower second premolar(17.4%)> lower incisor(15.9%);27.6%patients also have retention of deciduous teeth, the mandibular second deciduous molar are commom(76.9%).(3)21(72.4%) cases are angle class I malocclusion,8cases(27.6%) are angle class Ⅱ,27.6%patients have overbite of various degrees;31%patients have overjet of various degrees;34.5%patients have abnormalities in dental arch and bone mass development.(4)Modle analysis:13cases(44.8%) space analysis are crowd(10cases are Ⅰ°,3cases are Ⅱ°);100%patients are abnormal in Bolton analysis.13cases(44.8%) have deep surve of Spee,6cases(20.7%) have deep surve of Spee,10cases(34.5%) are normal.(5) Cephalometrics:17cases(58.6%) are skeletal class Ⅰ malocclusion,3cases(10.3%) are skeletal class Ⅱ malocclusion,9cases(31.0%) are skeletal class Ⅲ malocclusion.2. Detection of gene PAX9:(1)SNP:c.631+41g>a heterozygosity/homozygosity change(16cases,55.1%);(2) SNP:c.717-718CG>TC heterozygosity/homozygosity change(27cases,93.1%). There are6types change in this two sites.3. Detection of gene MSX1:(1)c.469+5G>A heterozygous mutation is a pathogenic mutation in a congenital non-syndromic oligodontia family.(2)SNP:C.119C>G homozygous mutation(1cases,3.4%), C.348C>T heterozygous mutation(3cases,10.3%), c.470-24t insert(2cases,6.9%), c.912+68c>t heterozygous mutation(10,34.5%).4. Corresponding relation between clinical phenotype and gene type: (1)only PAX9gene bases change are13cases (44.8%), only MSX1gene bases change are2cases (6.9%), both of two genes have changes are13cases (44.8%), no change is1cases (3.4%).(2) The more teeth missing, the more influence by PAX9base changes than MSX1.(3) Most of patients’missing teeth in the reserch are focused on front teeth area, in the missing teeth on molar area, PAX9maybe more stronger than MSX1.Conclusions:1.Patients of congenital non-syndromic hypodontia have malocclusion of various degrees due to different sexes, nationalities, regions, numbers and positions of missing teeth;2. PAX9gene c.717-718CG>TC heterozygous mutation might be a pathogenic cause for congenital non-syndromic hypodontia;3. MSX1gene c.469+5G>A heterozygous mutation is a pathogenic mutation in a family congenital non-syndromic oligodontia. And c.119C>G homozygous mutation and c.348C>T heterozygous mutation might be pathogenic causes for congenital non-syndromic hypodontia.4.PAX9gene may have synergy relationship with MSX1gene in congenital non-syndromic hypodontia patients. Compared with MSX1gene, when the more serious symptoms express, the more effects may be produced by PAX9.