Any primary immunodeficiency disorder has a direct impact on your immune system and causes defects in the body’s immune system. These disorders are passed down genetically from one or both parents. While there are more than 300 types of primary immunodeficiency disorders, they can be classified into 6 different categories, consisting of B cell (antibody) deficiencies, T cell deficiencies, a combination of B and T cell deficiencies, complement deficiencies, defective phagocytes, and idiopathic (in other words, unknown). Any sort of illness such as the flu or even just a cold can cause your immune system to weaken temporarily. As well, having asthma has been shown to cause a weakened immune system. Those who are patients with cancer are also known for being at a much higher risk of contracting an infection due to their weakened immune system caused both by the disease and the necessary treatments.