What distinguishes primary immunodeficiencies from secondary immunodeficiencies?

Primary immunodeficiencies are characterized by genetic mutations or hereditary factors that impair the immune system's ability to function properly. These immunodeficiencies typically manifest early in life, as they are often congenital, stemming from inherited defects in immune system components such as antibodies, T cells, or phagocytes.

In contrast, secondary immunodeficiencies arise from external factors that do not involve genetic mutations. These can result from a variety of causes, including infections (like HIV), malnutrition, certain medications (such as chemotherapy), or systemic diseases (like diabetes). Since secondary immunodeficiencies develop due to external influences rather than inherent flaws in the immune system, they can occur at any age, often in response to environmental factors or health conditions.

This distinction is essential for both diagnosis and treatment strategies in immunology, as the approach to managing primary and secondary immunodeficiencies can differ significantly based on their underlying causes.