Down syndrome

Down syndrome

1. Down Syndrome
 Down syndrome also called Trisomy 21, is a
condition in which a person is born with an
extra chromosome.
 Chromosomes contain hundreds, or even
thousands, of genes. Genes carry the
information that determines traits.
 With Down syndrome, the extra chromosome
causes delays in the way a child develops,
mentally and physically.
 The physical features and medical problems
associated with Down syndrome can vary
widely from child to child. While some kids
with DS need a lot of medical attention,
others lead healthy lives.
 Though Down syndrome can't be prevented,
it can be detected before a child is born.
 The health problems that may go along with
DS can be treated, and many resources are
available to help kids and their families who
are living with the condition.
TYPES

2. There are three types of Down syndrome:-
Trisomy 21
 Trisomy 21 means there’s an extra copy of
chromosome 21 in every cell.
 This is the most common form of Down syndrome.
Mosaicism
 Mosaicism occurs when a child is born with an extra
chromosome in some but not all of their cells.
 People with mosaic Down syndrome tend to have
fewer symptoms than those with trisomy 21.
Translocation
 In this type of Down syndrome, children have only
an extra part of chromosome 21.
 There are 46 total chromosomes. However, one of
them has an extra piece of chromosome 21
attached.

Symptoms

3.  Though the likelihood of carrying a baby with Down
syndrome can be estimated by screening during
pregnancy, you won’t experience any symptoms of
carrying a child with Down syndrome.

 At birth, babies with Down syndrome usually have
certain characteristic signs, including:-
 Flat facial features
 Small head and ears
 Short neck
 Bulging tongue
 Eyes that slant upward
 Atypically shaped ears
 Poor muscle tone
 An infant with Down syndrome can be born an
average size, but will develop more slowly than a
child without the condition.

 People with Down syndrome usually have some
degree of developmental disability, but it’s often
mild to moderate. Mental and social development
delays may mean that the child could have:-
 Impulsive behavior
 Poor judgment
 Short attention span
 Slow learning capabilities

4.  Medical complications often accompany Down
syndrome.
These may include:-
 Congenital heart defects
 Hearing loss
 Poor vision
 Cataracts (clouded eyes)
 Hip problems, such as dislocations
 Leukemia
 Chronic constipation
 Sleep apnea (interrupted breathing during
sleep
 Dementia (thought and memory problems)
 Hypothyroidism (low thyroid function)
 Obesity
 Late tooth growth, causing problems with
chewing
 Alzheimer’s disease later in life
 People with Down syndrome are also more prone to
infection.

 They may struggle with respiratory
infections, urinary tract infections, and skin
infections.

Causes

5.  Normally, at the time of conception a baby
inherits genetic information from its parents
in the form of 46 chromosomes: 23 from the
mother and 23 from the father.
 In most cases of Down syndrome, a child
gets an extra chromosome 21 — for a total
of 47 chromosomes instead of 46.
 It's this extra genetic material that causes
the physical features and developmental
delays associated with DS.
 Although no one knows for su re why DS
happens and there's no way to prevent the
chromosomal error that causes it, scientists
do know that women age 35 and older have
a significantly higher risk of having a child
with the condition.
 At age 30, for example, a woman has about
a 1 in 1,000 chance of conceiving a child with
DS. Those odds increase to about 1 in 400 by
age 35. By 40 the risk rises to about 1 in
100.
Affects
 Kids with Down syndrome tend to share
certain physical features such as a flat facial
profile, an upward slant to the eyes, small
ears, and a protruding tongue.

6.  Low muscle tone is also characteristic of
children with DS, and babies in particula r
may seem especially floppy.
 Though this can and often does improve over
time, most children with DS typically reach
developmental milestones — like sitting up,
crawling, and walking — later than other
kids.
 At birth, kids with DS are usually of average
size, but they tend to grow at a slower rate
and remain smaller than their peers.
 For infants, low muscle tone may contribute
to sucking and feeding problems, as well as
constipation and other digestive issues.
 Toddlers and older kids may have delays in
speech and self-care skills like feeding,
dressing, and toilet teaching.
 Down syndrome affects kids' ability to learn
in different ways, but most have mild to
moderate intellectual impairment.
 Kids with DS can and do learn, and are
capable of developing skills throughout their
lives.
 They simply reach goals at a different pace
— which is why it's important not to compare
a child with DS against typically developing

7. siblings or even other children with the
condition.
 Kids with DS have a wide range of abilities,
and there's no way to tell at birth what they
will be capable of as they grow up.
 While some kids with DS have no significant
health problems, others may experience a
host of medical issues that require extra
care. For example, almost half of all children
born with DS will have a congenital heart
defect.
 Kids with Down syndrome are also at an
increased risk of developing pulmo nary
hypertension, a serious condition that can
lead to irreversible damage to the lungs. All
infants with Down syndrome should be
evaluated by a pediatric cardiologist.
 Approximately half of all kids with DS also
have problems with hearing and vision.
Hearing loss can be related to fluid buildup in
the inner ear or to structural problems of the
ear itself.
 Vision problems commonly include
strabismus (cross -eyed), near - or
farsightedness, and an increased risk of
cataracts.

8.  Regular evaluations by an otolaryngologist
(ear, nose, and throat doctor), audiologist,
and an ophthalmologist are necessary to
detect and correct any problems before they
affect language and learning skills.
Diagnosis
 Two types of prenatal tests are used to
detect Down syndrome in a fetus:- screening
tests and diagnostic tests.

 Screening tests estimate the risk that a fetus
has DS; diagnostic tests can tell whether the
fetus actually has the condition.

 Screening tests are cost-effective and easy
to perform.

 But because they can't give a definitive
answer as to whether a baby has DS, these
tests are used to help parents decide
whether to have more diagnostic tests.

 Diagnostic tests are about 99% accurate in
detecting Down syndrome and o ther
chromosomal abnormalities.

 However, because they're performed inside
the uterus, they are associated with a risk of
miscarriage and other complications.

9.  For this reason, invasive diagnostic testing
previously was generally recommended only
for women age 35 or older, those with a
family history of genetic defects, or those
who've had an abnormal result on a
screening test.

 However, the American College of Obstetrics
and Gynecology now recommends that all
pregnant women be offered screening with
the option for invasive diagnostic testing for
Down syndrome, regardless of age.

Screening tests include:-
 Nuchal translucency testing:-
 This test, performed between 11 and 14
weeks of pregnancy, uses ultrasound to
measure the clear space in the folds of
tissue behind a developing baby's neck.

 This measurement, taken together with
the mother's age and the baby's
gestational age, can be used to calculate
the odds that the baby has DS.

 Nuchal translucency testing is usually
performed along with a maternal blood
test.

10.  The triple screen or quadruple screen:-
 These tests measure the quantities of
normal substances in the mother's blood.

 As the names imply, triple screen tests
for three markers; the quadruple screen
includes one additional marker and is
more accurate.

 These tests are typically offered between
15 and 18 weeks of pregnancy.


 Integrated screen:-
 This uses results from fir st-trimester
screening tests (with or without nuchal
translucency) and blood tests with a
second trimester quadruple screen to
come up with the most accurate
screening results.

 A genetic ultrasound:-
 A detailed ultrasound is often performed
at 18 to 20 weeks in conjunction with the
blood tests, and it checks the fetus for
some of the physical traits abnormalities
associated with Down syndrome.

 Cell free DNA:-

11.  This test analyzes fetal DNA found in the
mother’s blood. It can be done in the 1st
trimester and is more accurate at
detecting Trisomy 21 than standard
blood tests.

 Currently cell free DNA testing is only
offered to women at high risk of having a
baby with Down Syndrome.

Reference:-
 Kapitan Pediatrics Book
 GHAI Essential Pediatrics (Eighth Edition)
 Health line ( https://www.healthline.com )
 WebMd ( https://www.webmd.com )
 Mayo Clinic ( https://www.mayclinic.org )
 My Self