Home > D. Systemic pathology > Genetic and developmental anomalies > Chromosomal diseases > Constitutional trisomies > trisomy 18

trisomy 18

Thursday 27 January 2005

Edward Syndrome, trisomy E

Definition: Trisomy 18 (1/5000 live births) presents with a great phenotypic variability. Intrauterine growth retardation (IUGR) with normal or increased amniotic fluid volume, craniofacial dysmorphism (strawberry-shaped head, micrognathia, choroid plexus cyst), congenital heart disease, omphalocele, large cisterna magna, and abnormal extremities (clenched hands and rocker-bottom feet) are frequently observed anomalies.

At least 30% of affected fetuses have abnormal extremities (unilateral or bilateral), the most frequent one being clenched hand and radial aplasia.

Synopsis

- systemic anomalies

  • intra-uterine growth retardation (IUGR)
  • low feat activity
  • polyhydramnios
  • failure to thrive

- placental anomalies

  • small placenta
  • single umbilcal artery

- cardiovascular anomalies

  • ventricular septal defect
  • atrial septal defect
  • patent ductus arteriosus

- craniofacial anomalies

  • short eyelid fissures
  • small mouth
  • small jaw
  • microcephaly
  • epicanthal folds
  • low set malformed ears
  • ceft lip/palate
  • eye abnormalites (10%)

- limb anomalies

  • clenched hand: clenched fists with the index finger overlapping the 3rd and 4th fingers
  • absence of the distal crease on the 5th finger
  • low-arch dermal ridge pattern on the fingertips
  • nails underdeveloped
  • big toe shortened and bent backward (dorsiflexed)
  • underdeveloped or absent thumbs
  • bilateral club feet
  • rocker-bottom feet
  • webbed fingers and toes (syndactyly)
  • radial aplasia (5-10%)
  • arthrogryposis (joint contractures)

- visceral malformations

  • diaphragmatic anomalies
  • renal malformations
  • pulmonary malformations
    • pulmonary lobar anomalies

- redundant skin folds
- cryptorchidism
- spina bifida (6%)
- scoliosis
- omphalocele
- Cantrell pentalogy (#3232702#)

Epidemiology

Prevalence (Since 1961)7 studies: 1/3400 - 1/11000

- 1-5000 liveborn
- 1-5000 stillborn
- 20 - 30% die in the first month
- 90% die by age one

Cytogenetics

- trisomy - 95%
- translocation - 2%
- mosaic - 3%

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  • Small first toe in trisomy 18
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