franceschetti–klein syndrome franceschetti–klein syndrome franceschetti–klein syndrome (also known as "mandibulofacial dysostosis") is a syndrome that includes palpebral antimongoloid fissures, hypoplasia of the facial bones, macrostomia, vaulted palate, malformations of both the external and internal ear, buccal-auricular fistula, abnormal development of the neck with stretching of the cheeks, accessory facial fissures, and skeletal deformities.: 577 it is sometimes equated with treacher collins syndrome. franceschetti–klein syndromeother namesmandibulofacial dysostosisthis condition is inherited in an autosomal dominant manner.