Patients suffering from LAD have impaired cell surface expression of β2 heterodimers such as LFA-1, Mac-1, and p150/95, leading to defective leukocyte adhesion to endothelial cells, absence of diapedesis and substandard phagocytosis (Anderson and Springer, 1987). This evidence concerns the gene ITGB2 and leukocyte adhesion deficiency.