, ▁imm unos upp ression ▁ther ap ies ▁like ▁cort ic ost ero ids ▁may ▁be ▁pres cribed . ▁ ▁For ▁primary ▁imm un ode fic ien cies ▁that ▁are ▁caused ▁by ▁gen etic ▁mut ation ▁does ▁not ▁exist ▁a ▁caus al ▁ther apy ▁that ▁would ▁" rep air " ▁the ▁mut ation . ▁Although ▁there ▁is ▁a ▁ ▁th era pe ut ic ▁option , ▁gene ▁ther apy ▁which ▁has ▁been ▁in ▁a ▁trial ▁for ▁few ▁imm une ▁def ic ien cies ▁affect ing ▁the ▁h emat opo iet ic ▁system . ▁Over ▁the ▁past ▁two ▁dec ades ▁there ▁were ▁some ▁successful ▁treat ments ▁of ▁patients ▁with ▁specific ▁primary ▁imm un ode fic ien cies ▁( P ID ), ▁including ▁X - link ed ▁severe ▁combined ▁imm un ode fic iency ▁( SC ID ), ▁W isk ott – A ld rich ▁synd rome ▁and ▁met abol ic ▁conditions ▁such ▁as ▁le uk od yst ro phy . ▁ ▁Gene ▁ther apy ▁evol ved ▁in ▁the ▁ 9 0 s ▁from ▁using ▁of ▁g amm aret ro vir al ▁vectors ▁to ▁more ▁specific ▁self - in activ ating ▁vector ▁platforms ▁around ▁ 2 0 0 6 . ▁The ▁vir al ▁vectors ▁randomly ▁insert ▁their ▁sequences ▁into ▁the ▁genom es . ▁However , ▁it ▁is ▁rarely ▁used ▁because ▁of ▁a ▁risk ▁of ▁developing ▁post - tre at ment ▁T - cell ▁le uk emia ▁as ▁a ▁result ▁of ▁inter fer ing ▁tum or - supp ress or ▁gen es ▁▁ ▁and ▁because ▁of