Trisomy 18 orEdwards Syndrome By chahardolee, ehsan DMD2-D
Trisomy 18 is a genetic disorderin which a person has a third copyof material from chromosome 18,instead of the usual two copies.
Causes, incidence, and risk factorsTrisomy 18 is a somewhat commonsyndrome. It is three times more commonin girls than boys.The syndrome occurs when there is extramaterial from chromosome 18. The extramaterial affects normal development.
SymptomsClenched handsCrossed legsFeet with a rounded bottom (rocker-bottom feet)Low birth weightLow-set earsMental delayPoorly developed fingernailsSmall head (microcephaly)Small jaw (micrognathia)Undescended testicleUnusual shaped chest (pectus carinatum)
Signs and testsAn exam during pregnancy may show an unusually large uterus andextra amniotic fluid. There may be an unusually small placenta whenthe baby is born.A physical exam of the infant may show unusual fingerprint patterns.X-rays may show a short breast bone. Chromosome studies willshow trisomy 18, partial trisomy, or translocation.Other signs include:Hole, split, or cleft in the iris of the eye (coloboma)Separation between the left and right side of the abdominal muscle (diastasis recti)Umbilical hernia or inguinal hernia
There are often signs of congenital heart disease, suchas:Atrial septal defect (ASD)Patent ductus arteriosus (PDA)Ventricular septal defect (VSD)Tests may also show kidney problems, including:Horseshoe kidneyHydronephrosisPolycystic kidney
TreatmentTreatment of children with trisomy 18 isplanned on a case-by-case basis. Whichtreatments are used depend on thepatients individual condition.
PreventionTests can be done during pregnancyto find out if the child has this syndrome.Genetic testing is recommended forparents who have a child with thissyndrome and who want to have morechildren.