Protocadherins are a large family of cadherin-like cell adhesion proteins that are involved in the establishment and maintenance of neuronal connections in the brain. There are three protocadherin gene clusters, designated alpha, beta and gamma, all of which contain multiple tandemly arranged genes. PCDH17 is a 1,159 amino acid single-pass type I membrane protein that contains six cadherin domains. Expressed as multiple alternatively spliced isoforms, PCDH17 is thought to function as a calcium-dependent cell adhesion protein that may play a role in establishing cell-cell connections within brain tissue. The gene encoding PCDH17 maps to human chromosome 13, which houses over 400 genes, such as BRCA2 and RB1, and comprises nearly 4% of the human genome.