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Conditions >BardetBiedlsyndrome

Onthispage: Description Geneticchanges Inheritance DiagnosisAdditionalinformation Othernames Glossarydefinitions

ReviewedSeptember2013

WhatisBardetBiedlsyndrome?BardetBiedlsyndromeisadisorderthataffectsmanypartsofthebody.Thesignsandsymptomsofthisconditionvaryamongaffectedindividuals,evenamongmembersofthesamefamily.VisionlossisoneofthemajorfeaturesofBardetBiedlsyndrome.Lossofvisionoccursasthelightsensingtissueatthebackoftheeye(theretina)graduallydeteriorates.Problemswithnightvisionbecomeapparentbymidchildhood,followedbyblindspotsthatdevelopintheside(peripheral)vision.Overtime,theseblindspotsenlargeandmergetoproducetunnelvision.MostpeoplewithBardetBiedlsyndromealsodevelopblurredcentralvision(poorvisualacuity)andbecomelegallyblindbyadolescenceorearlyadulthood.ObesityisanothercharacteristicfeatureofBardetBiedlsyndrome.Abnormalweightgaintypicallybeginsinearlychildhoodandcontinuestobeanissuethroughoutlife.Complicationsofobesitycanincludetype2diabetes,highbloodpressure(hypertension),andabnormallyhighcholesterollevels(hypercholesterolemia).OthermajorsignsandsymptomsofBardetBiedlsyndromeincludethepresenceofextrafingersand/ortoes(polydactyly),intellectualdisabilityorlearningproblems,andabnormalitiesofthegenitalia.Mostaffectedmalesproducereducedamountsofsexhormones(hypogonadism),andtheyareusuallyunabletofatherbiologicalchildren(infertile).ManypeoplewithBardetBiedlsyndromealsohavekidneyabnormalities,whichcanbeseriousorlifethreatening.AdditionalfeaturesofBardetBiedlsyndromecanincludeimpairedspeech,delayeddevelopmentofmotorskillssuchasstandingandwalking,behavioralproblemssuchasemotionalimmaturityandinappropriateoutbursts,andclumsinessorpoorcoordination.Distinctivefacialfeatures,dentalabnormalities,unusuallyshortorfusedfingersand/ortoes,andapartialorcompletelossofthesenseofsmell(anosmia)havealsobeenreportedinsomepeoplewithBardetBiedlsyndrome.Additionally,thisconditioncanaffecttheheart,liver,anddigestivesystem.

HowcommonisBardetBiedlsyndrome?InmostofNorthAmericaandEurope,BardetBiedlsyndromehasaprevalenceof1in140,000to1in160,000newborns.Theconditionis

morecommonontheislandofNewfoundland(offtheeastcoastofCanada),whereitaffectsanestimated1in17,000newborns.ItalsooccursmorefrequentlyintheBedouinpopulationofKuwait,affectingabout1in13,500newborns.

WhatgenesarerelatedtoBardetBiedlsyndrome?BardetBiedlsyndromecanresultfrommutationsinatleast14differentgenes(oftencalledBBSgenes).Thesegenesareknownorsuspectedtoplaycriticalrolesincellstructurescalledcilia.Ciliaaremicroscopic,fingerlikeprojectionsthatstickoutfromthesurfaceofmanytypesofcells.Theyareinvolvedincellmovementandmanydifferentchemicalsignalingpathways.Ciliaarealsonecessaryfortheperceptionofsensoryinput(suchassight,hearing,andsmell).TheproteinsproducedfromBBSgenesareinvolvedinthemaintenanceandfunctionofcilia.MutationsinBBSgenesleadtoproblemswiththestructureandfunctionofcilia.Defectsinthesecellstructuresprobablydisruptimportantchemicalsignalingpathwaysduringdevelopmentandleadtoabnormalitiesofsensoryperception.ResearchersbelievethatdefectiveciliaareresponsibleformostofthefeaturesofBardetBiedlsyndrome.AboutonequarterofallcasesofBardetBiedlsyndromeresultfrommutationsintheBBS1gene.Another20percentofcasesarecausedbymutationsintheBBS10gene.TheotherBBSgeneseachaccountforonlyasmallpercentageofallcasesofthiscondition.Inabout25percentofpeoplewithBardetBiedlsyndrome,thecauseofthedisorderisunknown.InaffectedindividualswhohavemutationsinoneoftheBBSgenes,mutationsinadditionalgenesmaybeinvolvedincausingormodifyingthecourseofthedisorder.StudiessuggestthatthesemodifyinggenesmaybeknownBBSgenesorothergenes.TheadditionalgeneticchangescouldhelpexplainthevariabilityinthesignsandsymptomsofBardetBiedlsyndrome.However,thisphenomenonappearstobeuncommon,andithasnotbeenfoundconsistentlyinscientificstudies.ReadmoreabouttheBBS1andBBS10genes.SeealistofgenesassociatedwithBardetBiedlsyndrome.

HowdopeopleinheritBardetBiedlsyndrome?BardetBiedlsyndromeistypicallyinheritedinanautosomalrecessivepattern,whichmeansbothcopiesofaBBSgeneineachcellhavemutations.Theparentsofanindividualwithanautosomalrecessiveconditioneachcarryonecopyofthemutatedgene,buttheytypicallydonotshowsignsandsymptomsofthecondition.

WherecanIfindinformationaboutdiagnosisormanagementofBardetBiedlsyndrome?

TheseresourcesaddressthediagnosisormanagementofBardetBiedlsyndromeandmayincludetreatmentproviders.

GeneReview:BardetBiedlSyndromeGeneticTestingRegistry:BardetBiedlsyndromeMedlinePlusEncyclopedia:ObesityMedlinePlusEncyclopedia:Polydactyly

YoumightalsofindinformationonthediagnosisormanagementofBardetBiedlsyndromeinEducationalresourcesandPatientsupport.GeneralinformationaboutthediagnosisandmanagementofgeneticconditionsisavailableintheHandbook.Readmoreaboutgenetictesting,particularlythedifferencebetweenclinicaltestsandresearchtests.Tolocateahealthcareprovider,seeHowcanIfindageneticsprofessionalinmyarea?intheHandbook.

WherecanIfindadditionalinformationaboutBardetBiedlsyndrome?

YoumayfindthefollowingresourcesaboutBardetBiedlsyndromehelpful.Thesematerialsarewrittenforthegeneralpublic.

MedlinePlusHealthinformation(5links)GeneticandRareDiseasesInformationCenter InformationaboutgeneticconditionsandrarediseasesEducationalresourcesInformationpages(2links)PatientsupportForpatientsandfamilies(5links)

Youmayalsobeinterestedintheseresources,whicharedesignedforhealthcareprofessionalsandresearchers.

GeneReviews ClinicalsummaryGeneticTestingRegistryRepositoryofgenetictestinformation(1link)ClinicalTrials.gov LinkingpatientstomedicalresearchPubMed RecentliteratureOMIM Geneticdisordercatalog

WhatothernamesdopeopleuseforBardetBiedlsyndrome?

BBSLaurenceMoonBardetBiedlsyndromeLaurenceMoonBiedlsyndromeLaurenceMoonsyndromeLMBBSLMS

Formoreinformationaboutnaminggeneticconditions,seetheGeneticsHomeReferenceConditionNamingGuidelinesandHowaregenetic

Reviewed:September2013Published:August10,2015

ListerHillNationalCenterforBiomedicalCommunicationsU.S.NationalLibraryofMedicine ,NationalInstitutesofHealth

conditionsandgenesnamed?intheHandbook.

WhatifIstillhavespecificquestionsaboutBardetBiedlsyndrome?AsktheGeneticandRareDiseasesInformationCenter .

WherecanIfindgeneralinformationaboutgeneticconditions?TheHandbookprovidesbasicinformationaboutgeneticsinclearlanguage.

Whatdoesitmeanifadisorderseemstoruninmyfamily?Whatarethedifferentwaysinwhichageneticconditioncanbeinherited?Ifageneticdisorderrunsinmyfamily,whatarethechancesthatmychildrenwillhavethecondition?Whyaresomegeneticconditionsmorecommoninparticularethnicgroups?

Theselinksprovideadditionalgeneticsresourcesthatmaybeuseful.

GeneticsandHealthResourcesforPatientsandFamiliesResourcesforHealthProfessionals

WhatglossarydefinitionshelpwithunderstandingBardetBiedlsyndrome?

anosmiaautosomalautosomalrecessivebrachydactylycellcholesteroldiabetesdigestivedigestivesystemdisabilityendstagerenaldiseasegenegenitaliahypertensionhypogonadisminfertileinheritedkidneymotorperceptionperipheralpolydactylypopulationprevalencerecessiverenalrenaldiseaseretinastagesyndactylysyndrometissuevisualacuityYoumayfinddefinitionsfortheseandmanyothertermsintheGeneticsHomeReferenceGlossary.SeealsoUnderstandingMedicalTerminology.

References(10links)Theresourcesonthissiteshouldnotbeusedasasubstituteforprofessionalmedicalcareoradvice.Usersseekinginformationaboutapersonalgeneticdisease,syndrome,orconditionshouldconsultwithaqualifiedhealthcareprofessional.SeeHowcanIfindageneticsprofessionalinmyarea?intheHandbook.

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