Leukocyte adhesion deficiency type 1

• Definition: A genetic condition characterized by a defect in the leukocytic chemotaxis that results in decreased phagocyte activity
• Etiology
  • Autosomal recessive inheritance
  • Absence of the β2-integrin leukocyte adhesion surface molecule LFA-1 (CD18) prevents leukocytes from migrating to tissues during infection or inflammation.

Mnemonic

CD18 for leukocyte adhesion deficiency (LAD) type 1, because once you turn 18 you’re no longer a lad.

• Clinical features
  • Classic triad of LAD-1:
    1. Delayed separation of the umbilical cord (>30 days). HIGH-YIELD BUZZWORD.
    2. Recurrent bacterial infections, especially of skin and mucosal surfaces (e.g., omphalitis, cellulitis, perirectal abscesses).
    3. Lack of pus formation at infection sites (“sterile” abscesses) because neutrophils cannot migrate there.
  • Other common findings:
    • Impaired wound healing.
    • Severe gingivitis and periodontitis, leading to early tooth loss.
  • Features specific to LAD-2: Bombay (hh) blood group, intellectual disability, short stature, characteristic facial features.
• Diagnosis
  • Leukocytosis; however, neutrophils are absent at the site of infection
  • Flow cytometry: absent CD18, CD11a, CD11b, and CD11c