PTCHD2 is a 1,392 amino acid multi-pass membrane protein that contains one SSD (sterol-sensing) domain and belongs to the patched family. Expressed in retina, brain and testis, PTCHD2 localizes to endoplasmic reticulum and colocalizes with cholesterol. PTCHD2 overexpression leads to increased cholesterol levels, suggesting that PTCHD2 may play a role in cholesterol homeostasis. PTCHD2 is further hypothesized to act as a link between thyroid hormone and cholesterol metabolism. Existing as two alternatively spliced isoforms, PTCHD2 is thought to assist in the release of lipid-anchored secreted proteins and is encoded by a gene that maps to human chromosome 1p36.22.