Final answer:
Primary immunodeficiencies are genetic disorders that typically present shortly after birth or in early childhood, though some may manifest later in life. They include conditions such as chronic granulomatous disease and severe combined immunodeficiency disease.
Step-by-step explanation:
Primary immunodeficiencies most commonly present shortly after birth or in early childhood, as they are caused by genetic abnormalities that a person is born with. However, they may also become apparent later in life in some cases. These conditions include but are not limited to chronic granulomatous disease, X-linked agammaglobulinemia, selective IgA deficiency, and severe combined immunodeficiency disease (SCID), also known as 'bubble boy disease.' On the other hand, secondary immunodeficiencies are acquired due to disease, diet, or environmental exposures and are more likely to develop later in life. Examples of secondary immunodeficiencies include those caused by HIV/AIDS, malnutrition, or other environmental factors.