Protocadherins, which constitute the largest subgroup within the cadherin superfamily, are predominantly expressed in the nervous system and are probably involved in the regulation of neuronal recognition and connectivity (PMID: 17936607; 12231349; 17133224). The protocadherin subfamily can be further subdivided into three groups: the clustered protocadherins, comprising α-, β- and γ-protocadherins; δ-protocadherins; and others, many of which are solitary (PMID: 17133224). PCDHA2 (protocadherin alpha 2) is a single-pass type I membrane protein containing 6 cadherin domains. It may be involved in the establishment and maintenance of specific neuronal connections in the brain. Three isoforms produced by alternative splicing have been described (UniProt).