Downs Syndrome is a genetic condition caused in most cases by an extra gene.
Down’s Syndrome is a genetic condition caused in most cases by a presence of an extra chromosome. Dr John Langdon Down first described the condition in 1866 and in 1959, Professor Lejeune proved the presence of an extra chromosome 21. Whereas the usual number of chromosomes is 46, a person with Down’s has 47, causing disruption to growth and development. The extra gene can come from either the father or mother. It is thought the genetic accident occurs during the initial cell division following conception.
For reasons still being researched, the chance of a woman having a child with Down’s increases with age, particularly after 35. One thought is linked with the declining quality of the eggs with age. It appears the age of the father is a less significant factor. Smoking has been linked to Down’s Syndrome.
People with Down’s Syndrome share distinctive family characteristics and also have distinguishing features common to Down’s. These may be:
- delayed mental and social skills
- learning disabilities
- an average mental age achieved of 8 years
- eyes slanting upwards and outwards (known as the Mongoloid slant)
- a flat-shaped head at the back
- loose skin at the nape of neck
- a vertical fold of skin between the two lids at the inner corner of the eye called the epicanthic fold.
- a smaller mouth cavity
- a larger tongue often slightly protruding
- a face appearing slightly flatter
- a flat nasal bridge
- broad hands with short fingers and a little finger curving inwards
- the space between the first and second toe extended
- decreased muscle tone at birth
- below average birthweight
Down’s Syndrome babies often suffer the following:
- congenital heart defects
- early mortality as a result of heart abnormalities
- gastrointestinal abnormalities
- obstruction of the duodenum in the small intestine
- a higher than average incidence of acute lymphocytic leukaemia
- potential for visual problems
- frequent ear infections or hearing loss, and
- an increased susceptibility to infection
- A Down’s baby often requires surgery directly following birth.
here is no specific treatment for Down’s Syndrome. It is thought that parents of Down’s babies are at increased risk of parenting a subsequent baby with Down’s.
Down’s Syndrome can be detected early in pregnancy. A Triple Test can be carried out at 14-20 weeks. Because the results are inconclusive, you would be offered amniocentesis or cordocentesis . Alternatively, a Nuchal ultrasound scan tests the baby’s neck development for signs of Down’s Syndrome. Again it does not provide a definitive answer but it can show at a very early stage if there is a chance your baby has Down’s. If it shows a high risk, you will be offered amniocentesis or CVS.
Amniocentesis can be carried out from 14-26 weeks and involves passing a fine, hollow needle through the abdominal wall into the womb to collect a sample of amniotic fluid. The results can take three weeks but are considered accurate. Cordocentesis can be carried out from 18-24 weeks. The doctor inserts a needle through your womb and into one of the blood vessels in the baby’s umbilical cord. A tiny sample of blood is taken and analysed.
Check out our Antenatal Testing section for information on ultrasound scans and invasive tests