Leukocyte adhesion deficiency

Leukocyte-adhesion deficiency
Classification and external resources
OMIM	116920
eMedicine	ped/1302
MeSH	D018370
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Leukocyte adhesion deficiency (LAD), is a rare autosomal recessive disorder characterized by immunodeficiency resulting in recurrent infections. LAD is currently divided into three subtypes: LAD1, LAD2, and the recently described LAD3, also known as LAD-1/variant. In LAD3, the immune defects are supplemented by a Glanzmann thrombasthenia-like bleeding tendency.

LAD was first recognized as a distinct clinical entity in the 1970s. The classic descriptions of LAD included recurrent bacterial infections, defects in neutrophil adhesion, and a delay in umbilical cord sloughing. The adhesion defects result in poor leukocyte chemotaxis, particularly neutrophil, inability to form pus and neutrophilia.

Individuals with LAD suffer from bacterial infections beginning in the neonatal period. Infections such as omphalitis, pneumonia, gingivitis, and peritonitis are common and often life-threatening due to the infant's inability to properly destroy the invading pathogens. These individuals do not form abscesses because granulocytes cannot migrate to the sites of infection.

Types of leukocyte adhesion deficiency include LAD1, LAD2, and LAD3. LAD1 is the most common.

Patients with LAD1 have an inherited molecular defect that causes a deficiency of the β-2 integrin subunit, also called CD18, which is encoded by the ITGB2 gene found on chromosome 21. This subunit is involved in the formation of the β-2 integrins (LFA-1, Integrin alphaXbeta2, and Mac-1/CR3) by dimerization with different CD11 subunits.

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