Describing, defining and comprehending the complex workings of the human body is quite complex. The immune system plays an enormous role with the inter workings of the human body. When the fundamental system, in this case the immune system, does not develop, or function as it should the entire body is affected.
Basically, your sick a lot more than other people. A cold or “virus” has the potential to kill you, every virus ends with months of infections. Etc., eventually, the Immune’s system organs begin to fail. Autoimmunity diseases begin appearing. Often , autoimmune diseases appear long before a definitive diagnosis of a Primary Immunodeficiency. Autoimmune diseases are a result of your immune system attacking itself, your own organs. For me, the illnesses began very young. Your constantly sick. Some are worse than others, and are hospitalized frequently. Some are Leary of hospitals and refuse to go–unless knocking at deaths door. That would be me. The Jeffrey Moddell Foundation illustrates “Symptom Checkers”: