简介：Objective:Toinvestigateimmune-relatedgeneticbackgroundinbilateralsuddensensorineuralhearingloss(SSNHL).Casereportandmethods:Thecaseisa45-year-oldmanpresentingwitha7-yearhistoryofbilateralprofoundSSNHL.Bloodbiochemicaltestingdemonstratedincreasedlevelsoftotalcholesterol(5.88mmol/L).TestsforhepatitisBshowedapositiveantibodyagainstthehepatitisBcoreantigen.ComplementC3wasbelowthenormalvalue,andcomplementC4andIgGwereinthelowerrangeofnormalvalues.CTimagesshowedanormalinnerearandvestibularaqueductbutroundwindowmembranousossificationonbothsides.Atotalnumberof232immuneassociatedgenesweresequencedusingthenextgenerationsequencingtechnique.Results:Mutationsweredetectedin5genes,includingthephosphoinositide3-kinasecatalyticsubunitdelta(PIK3CD),caspaserecruitmentdomain-containingprotein9(CARD9),complementfactorH-related(CFHR2),immunoglobulinlambda-likepolypeptide1Protein(IGLL1),andtransmembranechannel-likegenefamily8(TMC8).InthePIK3CDgene,aC896Tsubstituteinexon7wasdetected.Thismutationcausesprimaryimmunodeficiencyandisanautosomaldominantdisease.Conclusion:ThePIK3CDC896TmutationresponsibleforprimaryimmunodeficiencymaycontributetotheonsetofbilateralSSNHLwithsubsequentrapidprogression.