目的·评估配对盒基因9（paired box gene 9，PAX9）突变非综合征型先天缺牙（non-syndromic tooth agenesis，NSTA）患者的牙颌面表型。方法·对2016年1月—2023年12月于上海交通大学医学院附属第九人民医院口腔第二门诊部就诊的NSTA患者进行全外显子组测序，筛查PAX9突变患者。对筛查到的患者采用曲面体层摄影片评估缺牙的位置和数目，采用X射线头影测量评估患者的牙颌面畸形情况。结果·7例PAX9突变的NSTA患者纳入研究，男性3例（42.9%），女性4例（57.1%）。患者首诊年龄7~31岁，平均（19.7±8.0）岁。7例患者均携带PAX9杂合突变，其中4例为错义突变，3例为移码突变。平均缺失恒牙（15.9±2.9）颗，上颌缺失数［（9.6±2.6）颗］略多于下颌［（6.3±2.4）颗］（P=0.030）。上颌第二磨牙（100.0%）、上颌尖牙（85.7%）、下颌第二前磨牙（85.7%）为最常见的缺失位点，下颌侧切牙（14.3%）、下颌尖牙（14.3%）为最少缺失的位点。移码突变的患者缺牙数［（18.3±2.1）颗］多于错义突变［（14.0±1.8）颗］（P=0.032）。X射线头影测量结果显示：PAX9突变成年患者上牙槽座角（angle sella-nasion-subspinale，SNA）、颌凸角（angle nasion-subspinale-subspinale-porion，NA-APo）和前颅底长度（sella-nasion，S-N）均明显小于正常参考范围，提示上颌后缩，前颅底矢状向发育不足；面角（frankfort horizontal plane-nasion-porion，FH-NPo）大于参考值、Y轴角（Y axis）小于参考值，提示下颌前伸；上/下牙槽座角（angle subspinale-nasion-supramental，ANB）小于参考值，提示骨性Ⅲ类错畸形；上中切牙角（angle upper central incisor-nasion-subspinale，angle U1-NA）大于参考值，提示上中切牙唇倾；下中切牙-下颌平面角（angle lower central incisor-mandibular plane，IMPA）、下中切牙凸度（lower central incisor-nasion-supramental，L1-NB）小于参考值，提示下中切牙舌倾，上下前牙反倾向。结论·较为全面地报道了PAX9突变NSTA患者的牙颌面表型，有利于进一步理解PAX9在人类颌面部发育中的作用。

Objective ·To evaluate the dentofacial phenotype in non-syndromic tooth agenesis (NSTA) patients with paired box gene 9 (PAX9) mutation. Methods ·Patients with NSTA who visited the Department of Second Dental Center of Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, between January 2016 and December 2023 received whole-exome sequencing to screen PAX9 mutation. The location and number of missing teeth were evaluated by oral pantomography, and dentofacial deformities were evaluated by X-ray cephalometrics. Results ·Seven patients with PAX9 mutation were included in the study, including 3 males (42.9%) and 4 females (57.1%). The patients were 7?31 years old at first visit, with a mean age of (19.7±8.0) years old. All the 7 patients were PAX9 heterozygotes, of which 4 were missense and 3 were frameshift. The average number of missing teeth was 15.9±2.9. The number of missing teeth in maxilla (9.6±2.6) was slightly higher than that in mandible (6.3±2.4) (P=0.030). Maxillary second molar (100.0%), maxillary canine (85.7%) and mandibular second premolar (85.7%) were the three most common missing teeth, while mandibular lateral incisor (14.3%) and mandibular canine (14.3%) were the two least missing teeth. Patients with frameshift mutation had more missing teeth (18.3±2.1) than those with missense mutation (14.0±1.8) (P=0.032). X-ray cephalometrics analysis results showed that the angle sella-nasion-subspinale (SNA), angle nasion-subspinale-subspinale-porion (NA-Apo) and sella-nasion (S-N) in adult patients with PAX9 mutation were significantly lower than the normal reference values, suggesting a shorter anterior cranial base and maxillary length. The frankfort horizontal plane-nasion-porion (FH-NPo) was higher than the reference value, and the Y-axis was lower than the reference value, indicating a more prognathic mandible. The angle subspinale-nasion-supramental (ANB) was lower than the reference value, indicating a skeletal angle Ⅲ malocclusion. The angle upper central incisor-nasion-subspinale (angle U1-NA) was higher than the reference value, indicating a lip inclination of maxillary central incisor. The angle lower central incisor-mandibular plane (IMPA) and lower central incisor-nasion-supramental (L1-NB) were lower than the reference values, indicating a retroclination of the mandibular central incisor, and crossbite in the maxillary and mandibular anterior teeth. Conclusion ·The dentofacial phenotype of PAX9-mutated patients with NSTA is reported comprehensively. It is helpful to improve the understanding of the role of PAX9 in human maxillofacial development.