Indications for testing for Edwards syndrome (trisomy 18)
Trisomy 18 or Edwards Syndrome is a genetic disorder caused by the presence of an extra copy of all or part of chromosome 18.
In utero, the most common characteristic are
central nervous system anomalies
choroid plexus cysts
All infants born with Edwards syndrome present with
Structural heart defects
Some other physical findings (symptoms) may include:
Short breast bone
Underdeveloped thumbs and or nails
Webbing of the second and third toes
Clubfoot or Rocker bottom feet
Undescended testicles in males.
Microcephaly accompanied by a prominent back portion of the head
Low-set, malformed ears
abnormally small jaw (micrognathia)
Cleft lip/cleft palate
Narrow eyelid folds (palpebral fissures)
Widely-spaced eyes (ocular hypertelorism)
• Amniotic fluid
Discard the first 2 cc of fluid to reduce the risk of maternal cell contamination. Aseptically transfer 15-20 cc into sterile plastic conical tubes labeled with patient’s name and date of birth.
Aseptically transfer 5-10mg into sterile plastic conical tubes containing sterile transport medium. Label tube with patient’s name and date of birth.
• Peripheral blood
Collect 5-10 cc whole blood in a green top tube (sodium heparin). Label tube with patient’s name and date of birth.
A completed test requisition form must be included with every sample. A transport kit is available upon request.
FISH analysis can be performed as a SAT 24 hour study on interphase cells followed by complete cytogenetic analysis
Room temperature (DO NOT refrigerate, freeze or centrifuge)
24-hour laboratory testing for Edwards Syndrome can be performed by Fluorescence in situ hybridization on interphase nuclei followed by confirmatory cytogenetic analysis
Causes for Rejection
Frozen specimen, inappropriate container
FISH: 24 hours
Cytogenetic analysis: 7-10 days