Habsburg jaw / Austrian lip: Pathologic mandibular prognathism is a potentially disfiguring genetic disorder where the lower jaw outgrows the upper, resulting in an extended chin. It is sometimes a result of acromegaly.

This condition is colloquially known as Habsburg jawHabsburg lip or Austrian Lip. The trait is easily traceable in portraits of Habsburg family members.

The traits that were common to royal families are believed to have been passed on and exaggerated over time through royal intermarriage which caused acute inbreeding. Due to the large amount of politically motivated intermarriage among Habsburgs, the dynasty was virtually unparalleled in the degree of its inbreeding. Charles II of Spain is said to have had the most pronounced case of the Habsburg jaw on record. His jaw was so deformed that he was unable to chew.

The most common treatment for mandibular prognathism is a combination of Orthodontics and Orthognathic surgery.  Orthodontic treatment can involve braces, removal of teeth, or a mouthguard. The treatment starts with Orthodontic treatment to prepare patient for Orthognathic surgery. After the Surgery, post surgical Orthodontic treatment to finish and detail the new occlusion.