Infantile LAD-like disease due to RAC2 deficiency

Infantile leukocyte adhesion deficiency (LAD)-like disease due to RAC2 deficiency is an extremely rare primary immunodeficiency disorder caused by mutations in the RAC2 gene. RAC2 encodes a small GTPase protein that plays a critical role in neutrophil function, including chemotaxis, superoxide production, and degranulation. This condition closely mimics leukocyte adhesion deficiency syndromes, presenting in infancy with severe, life-threatening bacterial infections, poor wound healing, and marked leukocytosis (elevated white blood cell counts) despite impaired neutrophil migration to sites of infection. Affected infants typically develop omphalitis (infection of the umbilical cord stump), skin abscesses, perirectal abscesses, and soft tissue infections shortly after birth. The disease primarily affects the immune system, specifically the innate immune response mediated by neutrophils. Although neutrophil counts are often elevated in the blood, these cells are functionally defective, failing to properly migrate to and combat infections at tissue sites. Patients may also demonstrate defects in neutrophil oxidative burst activity and chemotaxis. Without treatment, the condition can be fatal in early life due to overwhelming infections. The primary curative treatment for this condition is hematopoietic stem cell transplantation (HSCT), which can restore normal neutrophil function. Supportive care includes aggressive antibiotic and antifungal prophylaxis to prevent and treat infections. Granulocyte colony-stimulating factor (G-CSF) may be used as a temporizing measure. Early diagnosis and referral to specialized immunology centers are essential for optimal outcomes.

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