What is Klinefelter Syndrome? Klinefelter Syndrome (kline-fel-ter), also known as 47,XXY, is a genetic condition where ...SkiptomaincontentYouarehereMenshealthKlinefeltersyndromeWhatisKlinefelterSyndrome?Whatarethesymptoms?Whatarethecauses?Howisitdiagnosed?Whattreatmentoptionsarethere?Yourdoctor’sappointmentResourcesandvideosWhatisKlinefelterSyndrome?KlinefelterSyndrome(kline-fel-ter),alsoknownas47,XXY,isageneticconditionwhereyouhaveanextraXchromosome.It’scongenital,whichmeansthatyou’rebornwithit.KlinefelterSyndromeisacommonchromosomaldisorder,affectingonein550men.However,manypeoplewithKlinefelterSyndromeareneverdiagnosed.WhatarethesymptomsforKlinefelterSyndrome?KlinefelterSyndromeisthemostcommoncauseofhypogonadism,aconditionthatstopsyourbodyfromproducingspermandtestosterone.Testosteroneisthemajorandrogen(malesexhormone)inyourbody,asyouneeditfornormalreproductiveandsexualfunction.Thismeansthat,ifyouhaveKlinefelterSyndrome,it’slikelythatyou’reinfertile.Smalltesticles(aboutthesizeofagrape)afterpubertyareastrongindicationofKlinefelterSyndrome.OthersymptomsofKlinefelterSyndrome,whichsometimesbutnotalwaysoccur,include:TallerthanaverageheightReducedfacialhairReducedbodyhairReducedmusclestrengthBreastdevelopment(gynecomastia)OsteoporosisFemininefatdistribution(e.g.onthighs)VaricoseveinsLowenergy(lethargy).WhatcausesKlinefelterSyndrome?Wedon’tknowwhysomepeoplehaveanextraXchromosome.AlthoughKlinefelterSyndromeisageneticdisorder,it’srareforsiblingstohaveit.Howdoesdiagnosiswork?AdiagnosisofKlinefelterSyndromeisconfirmedwithbloodtests.Itcanbediagnosedbeforeorimmediatelyafterachildisborn. Inothercases,KlinefelterSyndromeisidentifiedduringchildhoodwhenlearningorbehaviouraldifficultiesdevelop,oraroundthetimeofpubertywhenexpectedphysicalchangesaredelayedordon’thappen.Becausethesymptomsaren’talwaysobvious,anadultmightnotbediagnoseduntiltheyseekmedicalhelpforinfertility,alossofsexdrive,orabonefracture.ThemajorityofKlinefeltercasesarediagnosedinadulthood.Wethinkthatasmanyas75%ofmenwit