▁in ▁nature ▁( i . e ., ▁caused ▁by ▁other ▁disease , ▁drug ▁treatment , ▁or ▁environmental ▁expos ure ▁to ▁to x ins ). ▁Most ▁primary ▁imm un ode fic ien cies ▁are ▁gen etic ▁dis orders ; ▁the ▁majority ▁are ▁diagn osed ▁in ▁children ▁under ▁the ▁age ▁of ▁one , ▁although ▁mil der ▁forms ▁may ▁not ▁be ▁recognized ▁until ▁ad ul th ood . ▁While ▁there ▁are ▁over ▁ 4 3 0 ▁recognized ▁P ID s ▁as ▁of ▁ 2 0 1 9 , ▁most ▁are ▁very ▁rare . ▁ ▁About ▁ 1 ▁in ▁ 5 0 0 ▁people ▁in ▁the ▁United ▁States ▁are ▁born ▁with ▁a ▁primary ▁imm un ode fic iency . ▁ ▁Im m une ▁def ic ien cies ▁can ▁result ▁in ▁persistent ▁or ▁rec urr ing ▁in fe ctions , ▁auto - infl am mat ory ▁dis orders , ▁tum ors , ▁and ▁dis orders ▁of ▁various ▁org ans . ▁ ▁There ▁are ▁currently ▁limited ▁treat ments ▁available ▁for ▁these ▁conditions ; ▁most ▁are ▁specific ▁to ▁a ▁particular ▁type ▁of ▁P ID . ▁Research ▁is ▁currently ▁evalu ating ▁the ▁use ▁of ▁stem ▁cell ▁trans pl ants ▁( HS CT ) ▁and ▁experimental ▁gene ▁ther ap ies ▁as ▁a ven ues ▁for ▁treatment ▁in ▁limited ▁subsets ▁of ▁P ID s . ▁ ▁Sign s ▁and ▁sympt oms ▁The ▁precise ▁sympt oms ▁of ▁a ▁primary ▁imm un ode fic iency ▁depend ▁on ▁the ▁type ▁of ▁defect . ▁Gener ally , ▁the ▁sympt oms ▁and ▁signs ▁that ▁lead ▁to ▁the ▁diagn