EF-CAB4A is a 399 amino acid protein belonging to the EFCAB4 family. Containing two EF-hand domains, EF-CAB4A may be involved in store-operated Ca2+ entry (SOCE). EF-CAB4A exists as three alternatively spliced isoforms, and is encoded by a gene mapping to human chromosome 11p15.5. With approximately 135 million base pairs and 1,400 genes, chromosome 11 makes up around 4% of human genomic DNA and is considered a gene and disease association dense chromosome. 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.