[4] Congenital hemifacial enlargement in which mature lipocytes invade adjacent tissue.

Phenotypic features include soft-tissue and skeletal hypertrophy and regional macrodontia.

[6][4] The mutation is de novo and mosaic meaning it's new, not inherited and not occurring in every cell.

One of the DNA nucleotides was altered, causing a change in the amino acid put being into the protein, referred to as a missense mutation, and for PROS, this gives an overactivity, "gain-of-function".

Due to the infiltrating fat in important facial structures complete excision of the overgrowth is often impossible and there is a high risk of regrowth after resection.