單一門牙症候群主要是軀幹中軸少見的疾病之一。頭顱中央包含頭骨、上頷骨、牙齒、鼻咽、甚至腦部和軀體都會有缺現。其中的病理原因目前不詳，目前已知一基因突變會形成。它主要的改變在sonic hedgehog (SHH) 基因的7q36 位子。當診斷出來之後的治療主要是依據臨床異常表現再給予適當的處置。我們報告此一病例，主要是以鼻中隔狹窄而呼吸困難表現。此病患經保守治療免於開刀而症狀緩解。

Solitary median maxillary central incisor (SMMCI) syndrome is an uncommon disease with a complex disorder of midline developmental defects involving the midline structures of the head, including the cranial bones, maxilla, and dentition, nasal airways, and sometimes the brain or even other midline structures of the body. The etiology remains uncertain, but a missense mutation in the SHH gene at 7q36 may be associated with this syndrome. Treatment for SMMCI syndrome depends upon the individual anomalies. We therefore report a case of SMMCI syndrome with midnasal stenosis, who successfully underwent conservative treatment via an endotracheal tube dilatation procedure for her respiratory distress condition.