Leukocyte adhesion deficiency type 1 (LAD-1) is a phenotypically variable immune deficiency characterized by recurrent bacterial and fungal infections, slow wound healing, periodontitis and impaired pus formation. Delayed separation of the umbilical cord may be the first sign of the disorder in an infant. Patients have absent or severely reduced expression of beta-2 integrin (CD18 antigen) on the surface of their leukocytes. CD18 antigen is involved in adhesion and transmigration of human leukocytes in vivo, and thus patients with LAD-1 have impaired accumulation of myeloid leukocytes at extravascular sites. Treatment by bone marrow transplantation has been successful in several reported cases.
A severe and very rare form of LAD, known as LAD-2, has been identified and linked to a different gene, SLC35C1, in MIM 266265, Congenital Disorder of Glycosylation Type IIc. LAD-2 patients also have growth and mental retardation. This test does not examine SLC35C1.