Which statement best describes the characteristics of primary immunodeficiency diseases (PID)?

• A. They are predominantly auto-inflammatory syndromes.
• B. They are not genetic disease.
• C. They are genetic diseases.
• D. They are predominantly complement deficiencies.

Answer: (C)

Primary immunodeficiency diseases are congenital disorders caused by inherited genetic mutations that disrupt components of the immune system, leading to increased susceptibility to infections from early life. Because these defects arise from genetic changes present at birth, they are best described as genetic diseases. The spectrum includes problems in humoral and cellular immunity, phagocytes, and the complement system, so while certain specific deficiencies (like a complement defect) exist within this group, the defining feature is the genetic basis rather than being acquired or non-genetic. Auto-inflammatory syndromes involve innate immune dysregulation and are not the central descriptor of PID, reinforcing that the key point is their inherited genetic origin.