Klinefelter Syndrome (47, XXY) is a chromosomal variation in males in which one extra X chromosome is present, resulting in a 47,XXY karyotype. The extra X ...ScrollToTopAboutNewsEventsContactPODCASTStoredonateMenuforPatientsandFamiliesInformation&ResourcesRareDiseaseInformationRareDiseaseVideoLibraryPatientandCaregiverResourceCenterInformationonClinicalTrialsandResearchStudiesCOVID-19ResourcesHelptoAccessMedicationsPatientAssistanceProgramsOtherFinancialAssistanceConnectwithOthersFindaPatientOrganizationRareDiseaseDay®PatientStoriesTakeActionAttendEventsAdvocateSupportCloseforPatientOrganizationsJoinMembershipNetworkValueofMembershipMembershipCriteriaApplyforMembershipNonprofitResourcesMemberResourcesRareLaunch®WebinarSeriesCOVID-19RapidResponseLeadershipSeriesOtherWaystoPartnerGrowyourorganizationPatientRegistriesAdvocacyRareDiseaseDay®RDCA-DAPMembershipProfilesAboutourMembersMemberListRareCancerCoalitionCloseforCliniciansandResearchersResourcesResourcesforMedicalProfessionalsRareDiseaseInformationResourcesforyourPatientsContinuingMedicalEducationResearchOpportunitiesResearchGrantProgramRequestsforProposalsResearchGrantRecipientsConnectLendYourExpertiseRareDiseaseDay®CloseNORDRareDiseaseAdvocacyNORD’sPolicyinActionIssueOverviewsNORDontheIssuesPolicySteeringCommitteeNORDStateReportCardNationalPartnershipsTakeActionLocallyJointheRareActionNetwork®ProjectRDACContactYourRepresentativesTakeActionRareInsights®RareInsights®5MythsAboutOrphanDrugsandtheOrphanDrugActCloseGetInvolvedDonateNowGiveWaystoGiveDonatetoResearchNORD®StoreEducateEducationalInitiativesRaiseAwarenessIdentifyRareDiseaseExpertsJoinParticipateinEventsBecomeaMemberRareCancerCoalitionEmploymentOpportunitiesCorporateCouncilAbouttheCorporateCouncilCurrentMembersCouncilCodeofConductJointheCouncilCloseHome/ForPatientsandFamilies/RareDiseaseInformation/47,XXY(KlinefelterSyndrome)RareDiseaseDatabase0-9•A•B•C•D•E•F•G•H•I•J•K•L•M•N•O•P•Q•R•S•T•U•V•W•X•Y•ZPrint47,XXY(KlinefelterSyndrome)NORDgratefullyacknowledgesDr