Andersons pediatric cardiology 2074
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Hernias
Renalmalformation
Hypertension
40
20
20
FIG.77.5 FacialappearanceofWilliamssyndrome.
CardiacDefects
CHDsarediagnosedin75%ofthepatients,manifestingaselastinarteriopathy.
Infact,theabnormalelastinproteincharacteristicforthesyndromecauses
proliferationofarterialsmoothmuscleandintimalhyperplasiaresultingin
arterialstenosis,inparticularatsupravalvaraorticandpulmonaryarterylevels
(seeTable77.6),butalsoatmesentericandrenalarterylevelswithatendencyto
arterialhypertension.60–62
Supravalvaraorticstenosisisgenerallyaprogressivelesion,whichcanoccur
bothintheformoflocalizedhourglassnarrowingofthesupravalvarareaor
diffusenarrowingextendingintotheaorticarchandintotheoriginof
brachiocephalicarteries.Stenosesofpulmonaryarteries,onthecontrary,often
improvespontaneouslyinpatientswiththissyndrome.60
Thecharacteristicsofperipheralvascularity,coronaryarteries,andcerebral
vesselsofthesepatientsmaycomplicatebothhistoryortreatmentprocedures,
suchascardiaccatheterization,anesthesia,andsurgery.61,63
PatientswithWilliamssyndromeareatriskforsystemichypertensionand
myocardialanomalies,probablyduetoarterialstructuralanomalies.64Duetothe
possibleassociationwithcoronaryarterystenosis,thepreoperativeand
preinterventionalassessmentofthesechildrenmustincludecoronary
angiography,inparticularinpatientswithsupravalvaraorticstenosis.Inthis
syndrome,specificperioperativeprotocolsareindicatedtoreducethesurgical
risk.63
GeneticDefect
Thesyndromeiscausedbyasubmicroscopicdeletionofchromosome7q11.23,
encompassingtheelastingene(ELN).65Morethan20geneshavebeenmapped
insidethecommonlydeletedregion,spanningapproximately1.5megabases.
ManyoftheclinicalfeaturesofWilliamssyndrome,includingcardiacdefect,are
causedbythedeletionoftheelastingene.
MonogenicSyndromes
Rasopathies(NoonanSyndromeandRelated
Disorders)
ClinicalFeatures
RASopathiesareageneticallyheterogeneousandclinicallyvariablegroupof
disorderstransmittedthroughautosomaldominantinheritance.Noonan
syndromeandrelateddisorders,includingNoonansyndromewithmultiple
lentigines(alsoknownasLEOPARDsyndrome)andcardiofaciocutaneous
(CFC)andCostellosyndromescausedbymutationsaffectingseveralgenes
participatingintheRAS/MAPkinase(MAPK)signalingpathway.66,67
CommonclinicalfindingsinRASopathiesincludegrowthdefectsandfeeding
difficulties,distinctivefacialanomalies(Fig.77.6A–C),CHDs,webbedneck,
cryptorchidism,andchestanomalies(Table77.7).67
