Sonic Hedgehog Protein (SHH, VHH-1) belongs to the hedgehog protein family which includes Indian Hh, and Desert Hh. The Hh family is involved in cell fate and patterning during embryonic development, homeostasis, and adult tissue renewal. Aberrant Hh signaling activity can be associated with numerous birth defects and uncontrolled Hh pathway activation is linked to the development of several types of cancers. A defect in SHH has been linked in holoprosencephaly type 3 (HPE3), in which the developing forebrain fails to separate into right and left hemispheres, and ocular coloboma.
