Properdin deficiency

Properdin Deficiency

Diagram illustrating X-linked recessive inheritance pattern.

Properdin deficiency is a rare immunodeficiency disorder characterized by a deficiency of properdin, a protein that plays a crucial role in the complement system, which is part of the innate immune system. Properdin is the only known positive regulator of the complement alternative pathway, and its deficiency can lead to increased susceptibility to infections, particularly those caused by Neisseria meningitidis.

Pathophysiology

Properdin is a glycoprotein that stabilizes the alternative pathway convertases, C3bBb, on microbial surfaces, enhancing the opsonization and clearance of pathogens. In properdin deficiency, the lack of this stabilization results in impaired opsonization and phagocytosis of bacteria, leading to increased vulnerability to infections.

Genetics

Properdin deficiency is inherited in an X-linked recessive manner, meaning the gene responsible for the condition is located on the X chromosome. Males, having only one X chromosome, are more frequently affected, while females, with two X chromosomes, are typically carriers. Affected males inherit the defective gene from their carrier mothers.

Clinical Manifestations

Individuals with properdin deficiency are particularly susceptible to infections by encapsulated bacteria, especially Neisseria meningitidis, which can cause meningitis and septicemia. The severity of infections can vary, and some individuals may remain asymptomatic.

Diagnosis

Diagnosis of properdin deficiency involves laboratory tests to measure the levels of properdin in the blood. Genetic testing can confirm the presence of mutations in the properdin gene.

Management

Management of properdin deficiency focuses on preventing infections through vaccination and prophylactic antibiotics. In cases of infection, prompt treatment with appropriate antibiotics is crucial.

Related Pages

• Complement system
• Immunodeficiency
• Neisseria meningitidis
• X-linked recessive inheritance