The proximal short arm of chromosome 11 harbors several candidate genes that could explain the patient's signs and symptoms including ALX4 and EXT2, which are always present in the interstitial deletion of the short arm of chromosome 11 in PSS.
The full spectrum of PSS manifests when deletions are at least 2.1 Mb in size, spanning from D11S1393 to D11S1385/D11S1319 (44.6-46.7 Mb from the 11p terminus) and encompassing EXT2, responsible for multiple exostoses, and ALX4, causing parietal foramina.
Being proximal to EXT2 and ALX4, a 1.1 Mb region containing 12 annotated genes had been identified by deletion mapping to explain PSS phenotypes except multiple exostoses and parietal foramina.