Mutations in the small Rho-family GTPase, RAC2, critical for actin cytoskeleton remodeling and intracellular signal transduction, are associated with neonatal severe combined immunodeficiency (SCID), infantile neutrophilic disorder resembling leukocyte adhesion deficiency (LAD), and later-onset combined immune deficiency (CID). We investigated 54 RAC2 patients (23 previously reported) from 37 families. Data were collected from referring physicians and literature reports with updated …