這個基因編碼一種蛋白質，這種蛋白質有助于形成早期胚胎的模式它被認為是腹部神經管、前后肢軸和腹側體節的構圖中的關鍵誘導信號。與果蠅的sonic hedgehog蛋白具有序列和功能相似性的三種人類蛋白中，這種蛋白最為相似。蛋白質作為前體被自動催化裂解；n-末端部分可溶并包含信號活性，而c-末端部分參與前體處理。更重要的是，C-末端產物共價地將膽固醇部分附著到N-末端產物上，將N-末端產物限制在細胞表面并防止其在整個發育胚胎中自由擴散這種蛋白質或其信號通路的缺陷是無前腦（hpe）的一個原因，在這種疾病中，發育中的前腦不能正確地分為左右半球。hpe表現為面部畸形。也有人認為，該基因或其信號通路的突變可能與VACTERL綜合征有關，該綜合征的特征是脊椎缺損、肛門閉鎖、氣管食管瘺伴食管閉鎖、橈腎發育不良、心臟異常和肢體畸形此外，位于該基因上游的約1兆堿基的長程增強子的突變破壞肢體構型，并可導致前軸多指畸形。
This gene encodes a protein that is instrumental in patterning the early embryo. It has been implicated as the key inductive signal in patterning of the ventral neural tube, the anterior-posterior limb axis, and the ventral somites. Of three human proteins showing sequence and functional similarity to the sonic hedgehog protein of Drosophila, this protein is the most similar. The protein is made as a precursor that is autocatalytically cleaved; the N-terminal portion is soluble and contains the signalling activity while the C-terminal portion is involved in precursor processing. More importantly, the C-terminal product covalently attaches a cholesterol moiety to the N-terminal product, restricting the N-terminal product to the cell surface and preventing it from freely diffusing throughout the developing embryo. Defects in this protein or in its signalling pathway are a cause of holoprosencephaly (HPE), a disorder in which the developing forebrain fails to correctly separate into right and left hemispheres. HPE is manifested by facial deformities. It is also thought that mutations in this gene or in its signalling pathway may be responsible for VACTERL syndrome, which is characterized by vertebral defects, anal atresia, tracheoesophageal fistula with esophageal atresia, radial and renal dysplasia, cardiac anomalies, and limb abnormalities. Additionally, mutations in a long range enhancer located approximately 1 megabase upstream of this gene disrupt limb patterning and can result in preaxial polydactyly.
