<prompt> Leukocyte-adhesion deficiency 2 is due to the absence of ___.SelectinLFA-1MAC 1Sialyl-Lewis X  <response>: Leukocyte adhesion deficiencies LADs stem from inherited defects in adhesion molecules that impair leukocyte recruitment to sites of infection, resulting in recurrent bacterial infections.LAD1 is caused by defects in the β 2 chain that is shared by the integrins LFA-1 and Mac-1. LAD2 is caused by a defect in a fucosyl transferase that is required to synthesize functional sialyl-Lewis X, the ligand for E- and P-selectins.Reference-Robbins BASIC PATHOLOGY 10th edition pg-172 