Chromosomal Anomaly

1. EDWARDS
SYNDROME
TRISOMY 18

2. WHAT IS TRISOMY 18
 TRISOMY 18is a chromosomal condition , also known as EDWARDS
SYNDROME, associated with Abnormalities in parts of the body.
 INDIVIDUALS who are affected with trisomy 18 may have defects,slow growth
before birth and Abnormalies of other organs that develop before birth.
 The majority of fetuses diagnosed with Edwards syndrome, or trisomy
18, die either before birth or shortly after birth, Infants who survive into
childhood are often physically deformed and have serious cognitive
deficiencies

3. Causes of Trisomy 18
 It result from having three copies of chromosome 18 in each cell in the
body instead of the usual two copies, the extra genetic material
disarrange the normal course of development +/- 5% of the people
have an extra copy of chromosome in on only some of the bodys cells
and this condition is called Mosaic Trisomy 18
 The development of individuals with mosaic trisomy 18 may range from
normal to severely affected.
 When Edward’s syndrome is caused by an entire extra chromosome 18
it is called a primary trisomy.
 Another rare cause of Edward’s syndrome is an unbalanced
translocation which happens when an extra portion of chromosome 18
is attached to part of another chromosome and This can occur
because one of the baby's parents carries what is known as a
'balanced translocation

4. Causes of Trisomy 18
 It is possible to distinguish between the 2 causes of Trisomy by
looking at the chromosomes of the baby. Which can be done
during pregnancy or after pregnancy by testing the baby's blood. If
the baby's chromosomes have not been checked then it is also
possible to look at the chromosomes of the parents to see if either of
them carries a balanced translocation.
 Reports suggest that the risk of such errors (e.g. nondisjunction
during meiosis) may increase with advanced parental age.

5. Inheritance pattern
 Trisomy 18 occur as random events during the formation of eggs
and sperm
 It is not inherited in most cases
 Nondisjunction(an error in cell division), result in a reproductive cell
with an abnormal number of chromosome.
 If one of these atypical reproductive cells contributes to the genetic
makeup of child, he/she will have an extra chromosome 18 in each
of the bodys cells

6. 3 Types of Trisomy 18
 Full Trisomy 18: is the most type, where there is a extra chromosome
in the babys body.
 Partial Trisomy: The body only has a part of an extra chromosome
18, this type of trisomy 18 is very rare.
 Mosiac Trisomy 18: The extra chromosome 18 is only in some of the
bodys cells, very rare type of trisomy 18.

7. Symptoms of trisomy 18
 Babies with trisomy 18 are often born very small and frail. They
typically have many serious health problems and physical defects,
including:
 Cleft palate, defects of the lungs, Kidneys, Stomach and chest
deformity
 Slowed growth or severe development delays, small jaw, small head
 Some babies will have Heart defects which include a hole between
the heart upper or lower chambers.

8. Prognosis of Trisomy 18
 The prognosis of a genetic condition depends on many factors such
as the specific diagnosis, symptoms and particular signs
 The Prognosis of Trisomy 18 includes the following:
 Quality of life such as independence in daily activities.
 The life expentancy of a person with the disorder.
 How quickly the signs and symptoms worsen.
 Associated health issues and complications.

9. Sonographic findings of
Edwards syndrome
Various Sonographic features of Trisomy
18 include a Strawberry-shaped skull,
Diaphragmatic Hernia, Renal Anomalies
and Enlarged Cisterna Magna

10. Sonographic Findings
of Trisomy 18
Bilateral choroid cyst in a fetus with trisomy 18
are seen within the ventricles.
CPCs are usually see1% to 2% of the normal
pregnancy and are most common in the 2nd
Trimester, usually resolving by 28 Weeks of
gastation

11. Macrognatism : a condition where
the jaw
is undersized(macrognathia)

12. Sonographic Findings of Trisomy 18
Clubfoot. Image of the lower leg and foot demonstrates the bones of the
feet (arrows) lying in the same plane as the tibia and fibula
clubfoot clubfoot

13. Rockerbottom
Image of the lower leg and foot
demonstrating downward curvature of
the bottom of the foot.

14. Other Features of trisomy 18
 Sometimes single umbilical artery, Hydrocephalus. Intrauterine
Growth Restriction with polyhydramnios will be also
present and congenital heart disease, mainly ventricular septal
defect
 Clenched fist with overlapping fingers
 Many individuals with trisomy 18 die before birth or within the first
month due to the presence of several life threatening medical
problems up to 5-10% of children with trisomy 18 live past their first
year and these children often have severe intellectual disability.

15. How is Trisomy 18 Diagnosed
 The most accurate way to diagnose this condition is amniontesis or
taking cells from placenta to analyze their chromosomes.
 Ultrasound is often not accurate, after the baby is born signs can be
seen on the face or body by the doctors
 A scan may be done at the 1st trimester to look for a small
collection of fluid on the back of the baby's neck. The thickness of
this fluid filled area is measured (nuchal thickness) and if it is above
the normal range it might suggests the baby might have a
condition such as Trisomy 18.
 A chromosome blood test will be done to determine
chromosome abnormalities and to detect future trisomy 18 disorders
with the next pregnancy

16. Treatment
 Supportive medical care to help the child with the best quality of
live possible
 No cure for Edwards syndrome

17. References
 Boston Children's Hospital(2020).Trisomy 18 and 13 Symptoms & Causes[online] available
athttp://www.childrenshospital.org/conditions-and-treatments/conditions/t/trisomy-18-and-13/symptoms-and-
cause (accessed 28 August 2020)
 Careda, A &Carey, JC. (2012).The trisomy 18 syndrome. Orphanet Journal of Rare Diseases,7(1)
 Genetics Reference (2020).Trisomy 18 [online] available athttps://ghr.nlm.nih.gov/condition/trisomy-
18#synonyms (accessed 28 August 2020)
 NORD (National Organization for Rare Disorders)(2020). Trisomy 18 [online] available at https://rarediseases.org/rare-
diseases/trisomy-18-syndrome/ (Accessed 28 August 2020)
 Penny,SM.(2018).Abdomen & obstetrics and gynecology: Chromosomal Abnormalities.(2ed). Philaldepia,
Wolters Kluwer
 WebMD(2019).What is Trisomy 18 available[online] at https://www.webmd.com/baby/what-is-trisomy-
18#2 (accessed 27 August 2020)

18. Group 3
Sandile & Edonea