C2CD3 (C2 domain-containing protein 3), also known as FLJ34770, is a 2,353 amino acid protein that contains two C2 domains. C2 domains are regions of about 130 amino acid residues that are found in proteins that bind phospholipids. It is thought that calcium binding to the C2 domain induces an electrostatic potential change that enhances phospholipid binding, which suggests a role for the domain as an electrostatic switch. C2CD3 is expressed as five isoforms produced by alternative splicing events. The gene that encodes C2CD3 maps to human chromosome 11, which makes up around 4% of human genomic DNA. The chromosome 11 encoded Atm gene is important for regulation of cell cycle arrest and apoptosis following double strand DNA breaks. Atm mutation leads to the disorder known as ataxia-telangiectasia. The blood disorders Sickle cell anemia and β thalassemia are caused by HBB gene mutations. Wilms' tumors, WAGR syndrome and Denys-Drash syndrome are associated with mutations of the WT1 gene. Jervell and Lange-Nielsen syndrome, Jacobsen syndrome, Niemann-Pick disease, hereditary angioedema and Smith-Lemli-Opitz syndrome are also associated with defects in chromosome 11.