EFHC2 contains 3 DM10 domains, followed by 3 putative EF-hand motifs. There are two named isoforms produced by alternative splicing. EFHC2 can be used as a quantitative trait locus for fear recognition in Turner syndrome.

EF-HC2 is a 749 amino acid protein containing three DM10 domains and an EF-hand domain. EF-HC2 shares 41.6% homology with EF-HC1, and is widely expressed in peripheral tissues and central nervous system. The gene encoding EF-HC2 maps to human chromosome Xp11.3 and is critical for recognition of facial fear and harm avoidance. Turner syndrome, characterized by deficits in social cognition and recognition of facial fear, has been linked to the EF-HC2 gene. Deletion of the EF-HC2 gene may be associated with Norrie disease, an X-linked disorder that primarily effects the eye, and may also be linked to juvenile myoclonic epilepsy. EF-HC2 exists as two isoforms due to alternative splicing events.