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Martes, Marso 12, 2013


Alternate name: Trisomy 18

Characteristics/ Phenotype

Trisomy 18, also known as Edward’s syndrome, is a condition which is caused by an error in cell division, known as meiotic disjunction.  The child develops three copies of chromosome 18 in each cell of their body, instead of the usual two. Babies with Edward's syndrome will grow slowly in the womb and will have a low birthweight after birth. It may lead to severe intellectual and physical defects.

Doctors may suspect that a baby has Edward's syndrome just by their characteristic features, although the disease must be confirmed with genetic tests. Mosaic trisomy 18 may be very severe or hardly noticeable, depending upon the number of cells that have the extra chromosome. In rare cases, there is no extra chromosome present; rather, a portion of the long arm of chromosome 18 becomes attached to another chromosome during the formation of egg and sperm cells or very early in development of the embryo. In this case, the individual has two copies of chromosome 18 plus the additional material from chromosome 18 that is attached to another chromosome. This is known as translocation, and the extra genetic material causes the developmental abnormalities in the same way as the presence of an entire extra chromosome. 
The features of Edward’s syndrome are as follows:

Physically, signs of Edward’s syndrome include a small, abnormally shaped head(known as microcephaly), sometimes a strawberry shaped-head, a small jaw (known as micrognatia) and mouth, long fingers that overlap, with short fingernails and clenched fists, low-set ears and smooth rounded base feet. These patients also have medical problems from mild to worst; some gets heart and kidney problems, feeding problems in infancy, leading to poor growth, breathing problems, hernias in the wall of their tummy, part of the intestinal tract is outside the stomach (known as omphalocele),the esophagus doesn’t connect to the stomach (esophageal artesia), bone abnormalities, such as a curved spine is also common.

Unfortunately, most babies with Edward's syndrome are miscarried or stillborn.
A third of babies born alive will die within a month of birth because of life-threatening medical problems.

Only 5-10% of babies with full Edward's syndrome survives beyond one year, and will live with severe disabilities. Survival to adulthood is extremely rare in trisomy 18. However, a few reports have described individuals who survived to the teen or early adult years.

Trisomy 18 occurs in about 1 in 5,000-6,000 live-born infants. Although women of all ages can have a child with trisomy 18, the chance of having a child with this condition increases as a woman gets older. Up to 95% of fetuses with trisomy 18 die in the prenatal period (prior to delivery). Girls are affected more commonly than boys.

(47, XY, +18) or (47, XX, +18)

Can be diagnosed through:
Karyotyping, Prenatal testing for trisomy 18, Screening tests such as measurement of alpha fetoprotein (AFP) levels (sometimes referred to as a triple screen), Ultrasound, Analysis of fetal chromosomal material obtained during amniocentesis or chorionic villus sampling.

Trisomy 18 is not an inherited condition; it occurs as the result of random events during egg and sperm formation. The type of error that occurs is known as nondisjunction, and this leads to an egg or sperm cell with an abnormal number of chromosomes.

Treatments/ Recommendations
There is no cure for Edward's syndrome and the symptoms can be very difficult to manage. You are likely to need help from a wide range of different health professionals.
Your child may benefit from physiotherapy and occupational therapy, if limb abnormalities affect their movements. They may need to be fed through a feeding tube.
If infections arise, it may be treated. Transfusions may be made for low blood cell counts, and medications such as diuretics and/or digoxin to manage heart failure.  

As a parent carer, it's important that you look after your own health and wellbeing first before you commit to nurse your baby.
Measures that can be done includes nutritional support to your child and sincere love and care.


Genetic and Rare Diseases Information Center (GARD). "Trisomy 18." NIH Office of Rare Diseases Research. <>.

Genetics Home Reference. "Trisomy 18." U.S. National Library of Medicine. 30 Jan. 2012. <>.

"What Is Trisomy 18?" Trisomy 18 Foundation. 2010. <>.

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