WASp is the founding member of a gene family which also includes the broadly expressed N-WASP (neuronal Wiskott–Aldrich syndrome protein), SCAR/WAVE1, WASH, WHAMM, and JMY.

[7][8] The Wiskott–Aldrich syndrome (WAS) family of proteins share similar domain structure, and are involved in transduction of signals from receptors on the cell surface to the actin cytoskeleton.

These proteins, directly or indirectly, associate with the small GTPase CDC42, known to regulate formation of actin filaments, and the cytoskeletal organising complex, Arp2/3.

This localization ensures the actin polymers will be able to push through the plasma membrane and form filopodium required for cell motility.

Other functions of WASP depend on its activity as a scaffold protein for assembly of effective signalling complexes downstream of antigen receptor or integrin engagement.

Wiskott–Aldrich syndrome is a rare, inherited, X-linked, recessive disease characterized by immune dysregulation and microthrombocytopenia, and is caused by mutations in the WASp gene.

The WASp gene product is a cytoplasmic protein, expressed exclusively in hematopoietic cells, which show signalling and cytoskeletal abnormalities in WAS patients.

Other, less inactivating mutations affecting the WASp cause X-linked thrombocytopenia, or XLT, where there is usually detectable protein levels by flow cytometry.

A prospective gene therapy for Wiskott–Aldrich syndrome, OTL-103, uses autologous CD34+ lymphocytes that are transfected with a lentiviral vector to produce functional WASp.