Down syndrome is a genetic disorder caused by the presence of an extra chromosome 21. It is characterized by physical abnormalities like a flat face and short neck, as well as cognitive delays. The most common form is trisomy 21, where there are three copies of chromosome 21 instead of the typical two copies. Diagnosis is usually made prenatally through tests like amniocentesis or chorionic villus sampling. Treatment focuses on supporting development and managing any associated medical conditions through a team approach involving various therapists and doctors.
2. What is Down syndrome?
Down syndrome is a genetic disorder and the most
common autosomal chromosome abnormality in
humans, where extra genetic material from
chromosome 21 is transferred to a newly formed
embryo. These extra genes and DNA cause changes
in development of the embryo and fetus resulting in
physical and mental abnormalities. Each patient is
unique and there can be great variability in the
severity of symptoms.
3. What causes Down syndrome?
Normally, the human body has 23 pairs of chromosomes
(called autosomes) and two sex chromosomes
(allosomes).
Patients with Down syndrome, an error occurs in the
coming together of chromosome 21. The extra genetic
material is responsible for the developmental
abnormalities that occur. Instead of 46 chromosomes
plus two sex chromosomes, there are 47.
The most common error in chromosome replication is
trisomy 21, where the new cell gets three copies of
chromosome 21, instead of two. This accounts for about
95% of those patients with Down syndrome.
4. What are the signs and symptoms of
Down syndrome?
Commonly, there is a small head and short neck, a
flat face, and upward slanting eyes.
Ears are flat and positioned lower than “normal.”
The tongue protrudes and seems to be too large for
the mouth.
Hands tend to be wide, with short fingers and there
is just a single flexion crease in the palm.
Joints tend to be more flexible and muscles may lack
tone.
5. The patient may have growth retardation and though as a
baby may be normal size, will not grow as tall. Average
height for an adult male with Down syndrome is 5 ft 1 in
and for a female it is 4 ft 9 in.
Obesity occurs with ageing.
There is decreased mental function and the IQ may range
from mild disability (50 to 70) to moderate (35 to 50).
There can be language development delay both
from hearing impairment and speech delay. Gross motor
skills like crawling and walking can be slow to mature
and fine motor skills may take time to develop.
6. How is Down syndrome diagnosed?
Most often, Down syndrome is diagnosed while the
fetus is still in the uterus.
These include the following:
Amniocentesis: A needle is placed using ultrasound
guidance into the uterus to obtain a sample of
the amniotic fluid that surrounds the fetus. The
fetus' chromosomes can be analyzed, looking for
trisomy 21.
Chorionic villus sampling: Cells are taken from the
placenta for fetal chromosome analysis.
There is a small risk of miscarriage with these tests.
7. What is the treatment for Down syndrome?
Providing support and treatment for a patient with Down
syndrome is meant to improve their quality of life.
Infants with Down syndrome may experience
developmental delays including time to sit, crawl, walk,
and talk so parents need to know that developmental
delays are common in children with Down syndrome.
Using a team approach to care, physical therapists,
occupational therapists, and speech therapists may help
improve language, motor, and social skills to the
maximum achievable by the individual person.
8. Medical conditions associated with Down syndrome,
including those affecting the heart or the
gastrointestinal system, may require evaluation and
care, sometimes requiring surgery.
As the patient ages, the care and support needed will
depend upon the intellectual ability and physical
function achievable by the individual.