WASF1 and immunodeficiency disease: Nck-associated protein 1-like (NCKAP1L) is a hematopoietic lineage-specific regulator of the Nap1l subunit of the WAVE complex, which signals downstream of activated Rac to stimulate F-actin polymerization in response to engagement of various immune receptors, and NCKAP1L defects would lead to a novel syndrome combining immunodeficiency, lymphoproliferation, and hyperinflammation (32).