[2] Macrostomia is characterized as a physical abnormality that causes clefts to form on the face of affected individuals.

[3] The cleft associated with macrostomia is associated with improper or failed fusion of the mandibular and maxillary processes during embryonic development.

[3] This can lead to a variety of abnormalities involving skin, subcutaneous tissue, facial muscles, and the mucous membrane.

The outside of the ear on the affected side of the face appears as normal and a region of soft tissue connects the cleft to the right lateral posterior hard palate.

[3] This version of macrostomia is less severe because it does not affect the facial muscles and is not associated with any soft tissue or bone deformities.

Bones in the region remain unaffected and the phenotype appears as an indentation of the cheek rather than an open cleft.

[6] PTCH2 inhibits the smooth frizzled class receptor (SMO) which when active is responsible for increasing transcription rates of many genes involved with development and differentiation.

[7][8] PTCH2 (Val147Ile) is a loss of function mutation which results in a lack of control of cell growth during development and links it to macrostomia.