Three different types of syndromes have been identified: Leukocyte adhesion deficiency 1: Deficient or defective beta-2 integrin family Leukocyte adhesion deficiency 2: Absent fucosylated carbohydrate ligands for selectins Leukocyte adhesion deficiency 3: Defective activation of all beta integrins (1, 2, and 3) Type 1 results from mutations in the integrin beta-2 gene (ITGB2), encoding CD18 beta-2 integrins.