Trisomy 18, also known as Edward's Syndrome, is a genetic disorder caused by the presence of an extra copy of chromosome 18. It is three times more common in girls than boys and can cause physical abnormalities like clenched hands, crossed legs, and heart defects. Treatment is tailored to each individual child but the outcome is often poor as many children with Trisomy 18 die within the first year. Genetic testing during pregnancy can identify risks and help parents plan for care of an affected child.

1. Trisomy 18 or
Edward's Syndrome
By chahardolee, ehsan
DMD2-D

2. Trisomy 18 is a genetic disorder
in which a person has a third copy
of material from chromosome 18,
instead of the usual two copies.

3. Causes, incidence, and risk factors
Trisomy 18 is a somewhat common
syndrome. It is three times more common
in girls than boys.
The syndrome occurs when there is extra
material from chromosome 18. The extra
material affects normal development.

4. Symptoms
Clenched hands
Crossed legs
Feet with a rounded bottom (rocker-bottom feet)
Low birth weight
Low-set ears
Mental delay
Poorly developed fingernails
Small head (microcephaly)
Small jaw (micrognathia)
Undescended testicle
Unusual shaped chest (pectus carinatum)

5. Signs and tests
An exam during pregnancy may show an unusually large uterus and
extra amniotic fluid. There may be an unusually small placenta when
the baby is born.
A physical exam of the infant may show unusual fingerprint patterns.
X-rays may show a short breast bone. Chromosome studies will
show 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

6. There are often signs of congenital heart disease, such
as:
Atrial septal defect (ASD)
Patent ductus arteriosus (PDA)
Ventricular septal defect (VSD)
Tests may also show kidney problems, including:
Horseshoe kidney
Hydronephrosis
Polycystic kidney

7. Treatment
Treatment of children with trisomy 18 is
planned on a case-by-case basis. Which
treatments are used depend on the
patient's individual condition.

8. Prevention
Tests can be done during pregnancy
to find out if the child has this syndrome.
Genetic testing is recommended for
parents who have a child with this
syndrome and who want to have more
children.