DOCK8(Dedicator of cytokinesis 8) a member of the DOCK180 family of guanine nucleotide exchange factors. DOCK8 functions as a guanine nucleotide exchange factor (GEF) that may play a role in protein activation and is thought to influence Actin organization. Defects in the gene encoding DOCK8 are associated with the pathogenesis of autosomal dominant mental retardation (MRD2), possibly due to errors in Actin-based cytoskeletal structure. Mutations in this gene also result in the autosomal recessive form of the hyper-IgE syndrome, a rare disorder characterized by immunodeficiency, recurrent infections, eczema, increased serum IgE, eosinophilia and lack of connective tissue and skeletal involvement. Multiple isoforms of DOCK8 exist due to alternative splicing events.