唐氏综合症英文资料
-
Down syndrome
, or
Down's syndrome
(primarily
in the
United
Kingdom
),
trisomy
21
, or
trisomy
G
, is a
chromosomal
disorder
caused by the presence of all
or part
of an extra
21st
chromosome
. It is named after
John Langdon Down
, the
British
physician
who described the
syndrome
in 1866. The
disorder was identified as a
chromosome
21
trisomy
by
Jérôme
Lejeune
in
1959.
The
condition
is
characterized
by
a combination of major and minor
differences in structure. Often Down syndrome is
associated with some impairment of
cognitive
ability and
physical growth
, and a
particular
set
of
facial
characteristics.
Down
syndrome
in
a
fetus
can
be
identified
with
amniocentesis
during
pregnancy, or in a baby at birth.
Individuals
with
Down
syndrome
tend
to
have
a
lower
than
average
cognitive
ability,
often
ranging
from
mild
to
moderate
developmental
disabilities
.
A
small
number
have
severe to profound mental disability.
The
incidence
of Down
syndrome is estimated
at 1 per 800 to
1,000 births, although it is statistically much
more common with
older mothers. Other
factors may also play a role.
Many
of
the
common
physical
features
of
Down
syndrome
may
also
appear
in
people
with
[3]
a standard set of
chromosomes, including
microgenia
(an abnormally
small chin)
,
[4]
an
unusually
round
face,
macroglossia
(protruding
or
oversized
tongue),
an
almond
shape
to the
eyes
caused by an
epicanthic
fold
of the eyelid, upslanting
palpebral
fissures
(the separation
between the upper and lower eyelids), shorter
limbs, a
single
transverse
palmar crease
(a single instead of a
double crease across one or
both
palms,
also
called
the
Simian
crease),
poor
muscle
tone
,
and
a
larger
than
normal
space
between the big and second toes. Health concerns
for individuals with Down
syndrome
include
a
higher
risk
for
congenital
heart
defects
,
gastroesophageal
reflux
disease
, recurrent
ear infections
,
obstructive sleep apnea
, and
thyroid
dysfunctions.
Early
childhood intervention
, screening for
common problems, medical treatment
where
indicated,
a
conducive
family
environment,
and
vocational
training
can
improve
the
overall
development
of
children
with
Down
syndrome.
Although
some
of
the
physical
genetic
limitations
of
Down
syndrome
cannot
be
overcome,
education
and
proper
care
[5]
will improve
quality of life
.
Characteristics
Individuals
with Down syndrome may have some or all of the
following physical
[3]
characteristics:
microgenia
(abnormally small
chin)
, oblique eye fissures with
epicanthic
skin
folds
on
the
inner
corner
of
the
eyes
(formerly
known
as
a
mongoloid
[4]
fold
), muscle
hypotonia (poor muscle tone), a flat nasal bridge,
a single palmar
fold, a protruding
tongue (due to small oral cavity, and an enlarged
tongue near
[4]
the tonsils)
or
macroglossia
, a short
neck, white spots on the
iris
known as
[6]
Brushfield
spots
,
excessive joint
laxity including atlanto-axial instability,
congenital
heart
defects,
excessive
space
between
large
toe
and
second
toe,
a
single
flexion
furrow
of
the
fifth
finger,
and
a
higher
number
of
ulnar
loop
dermatoglyphs
.
[1][2]
Most
individuals
with
Down
syndrome
have
mental
retardation
in
the
mild
(
IQ
50
–
70)
[7]
to moderate (IQ
35
–
50) range,
with individuals having
Mosaic Down
syndrome
[8]
typically
10
–
30 points
higher.
In addition, individuals with
Down syndrome can
have serious
abnormalities affecting any body system. They also
may have a broad
head and a very round
face.
The
medical
consequences
of
the
extra
genetic
material
in
Down
syndrome
are
highly
variable
and
may
affect
the
function
of
any
organ
system
or
bodily
process.
The
health
aspects of Down
syndrome encompass anticipating and preventing
effects of the
condition,
recognizing
complications
of
the
disorder,
managing
individual
symptoms,
and assisting the
individual and his/her family in coping and
thriving with any
[7]
related
disability or illnesses.
Down syndrome can result from several
different genetic mechanisms. This results
in a wide variability in individual
symptoms due to complex gene and environment
interactions. Prior to birth, it is not
possible to predict the symptoms that an
individual
with
Down
syndrome
will
develop.
Some
problems
are
present
at
birth,
such
as
certain
heart
malformations.
Others
become
apparent
over
time,
such
as
epilepsy.
The most common
manifestations of Down syndrome are the
characteristic facial
features,
cognitive impairment,
congenital heart
disease
(typically a
ventricular
septal
defect
), hearing deficits (maybe due to
sensory-neural factors, or chronic
serous
otitis
media
,
also
known
as
Glue-
ear),
short
stature
,
thyroid
disorders,
and
Alzheimer's disease
. Other
less common serious illnesses include
leukemia
,
immune
deficiencies
, and
epilepsy
.
However,
health
benefits
of
Down
syndrome
include
greatly
reduced
incidence
of
many
[9]
common malignancies
except leukemia and testicular cancer
—
although it is, as
yet, unclear whether the reduced
incidence of various fatal cancers among people
with Down syndrome is as a direct
result of tumor-suppressor genes on chromosome
[10]
21,
because
of
reduced
exposure
to
environmental
factors
that
contribute
to
cancer
risk,
or
some
other
as-yet
unspecified
factor.
In
addition
to
a
reduced
risk
of
most
kinds
of
cancer,
people
with
Down
syndrome
also
have
a
much
lower
risk
of
hardening
[11]
of
the arteries
and
diabetic
retinopathy
.
Cognitive development
Cognitive development
in
children with Down syndrome is quite variable. It
is not
currently
possible
at
birth
to
predict
the
capabilities
of
any
individual
reliably,
nor
are
the
number
or
appearance
of
physical
features
predictive
of
future
ability.
The identification of the best methods
of teaching each particular child ideally
[12]
begins
soon
after
birth
through
early
intervention
programs.
Since
children
with
Down syndrome have a wide range of
abilities, success at school can vary greatly,
which
underlines
the
importance
of
evaluating
children
individually.
The
cognitive
problems that are
found among children with Down syndrome can also
be found among
typical children.
Therefore, parents can use general programs that
are offered
through the schools or
other means.
Language
skills
show
a
difference
between
understanding
speech
and
expressing
speech,
and commonly individuals with Down
syndrome have a speech delay, requiring
speech
[13]
[14]
therapy
to
improve
expressive
language.
Fine
motor
skills
are
delayed
and
often
lag
behind
gross
motor
skills
and
can
interfere
with
cognitive
development.
Effects
of the disorder on the development of
gross motor skills are quite variable. Some
children will begin walking at around 2
years of age, while others will not walk
until
age
4.
Physical
therapy,
and/or
participation
in
a
program
of
adapted
physical
education (APE),
may promote enhanced development of gross motor
skills in Down
[15]
syndrome
children.
Individuals with
Down syndrome differ considerably in their
language and
communication skills. It
is routine to screen for middle ear problems and
hearing
loss;
low
gain
hearing
aids
or
other
amplification
devices
can
be
useful
for
language
learning. Early communication
intervention fosters linguistic skills. Language
assessments can help profile strengths
and weaknesses; for example, it is common
for receptive language skills to exceed
expressive skills. Individualized speech
therapy
can
target
specific
speech
errors,
increase
speech
intelligibility,
and
in
some cases encourage
advanced language and literacy.
Augmentative and alternative
communication
(AAC)
methods,
such
as
pointing,
body
language,
objects,
or
graphics
are
often
used
to
aid
communication.
Relatively
little
research
has
focused
on
the
[16]
effectiveness of
communications intervention strategies.
In education,
mainstreaming
of children
with Down syndrome is becoming less
controversial
in
many
countries.
For
example,
there
is
a
presumption
of
mainstream
in
many
parts
of
the
UK.
Mainstreaming
is
the
process
whereby
students
of
differing
abilities
are
placed
in
classes
with
their
chronological
peers.
Children
with
Down
syndrome may not age
emotionally/socially and intellectually at the
same rates as
children without Down
syndrome, so over time the intellectual and
emotional gap
between children with and
without Down syndrome may widen. Complex thinking
as
required in sciences but also in
history, the arts, and other subjects can often
be beyond the abilities of some, or
achieved much later than in other children.
Therefore,
children
with
Down
syndrome
may
benefit
from
mainstreaming
provided
that
[17]
some
adjustments are made to the curriculum.
Some European countries such as
Germany
and
Denmark
advise a two-teacher
system,
whereby
the
second
teacher
takes
over
a
group
of
children
with
disabilities
within
the class. A popular
alternative is cooperation between
special schools
and
mainstream
schools.
In
cooperation,
the
core
subjects
are
taught
in
separate
classes,
which neither slows down the typical
students nor neglects the students with
disabilities. Social activities,
outings, and many sports and arts activities are
[18]
performed together, as
are all breaks and meals.
Fertility
Fertility amongst
both males and females is reduced; males are
usually unable to
father
children,
while
females
demonstrate
significantly
lower
rates
of
conception
[
citation
needed
]
relative to
unaffected individuals.
Approximately
half of the offspring
[19]
of
someone
with
Down
syndrome
also
have
the
syndrome
themselves.
There
have
been
[20][21]
only three recorded
instances of males with Down syndrome fathering
children.
Ethical issues
A
2002
literature
review
of
elective
abortion
rates
found
that
91
–
93%
of
pregnancies
[34]
in
the
United
Kingdom
and
Europe
with
a
diagnosis
of
Down
syndrome
were
terminated.
Data from the
National Down
Syndrome Cytogenetic Register
in the
United Kingdom
indicates that from 1989
to 2006 the proportion of women choosing to
terminate a
pregnancy following
prenatal diagnosis of Down Syndrome has remained
constant at
[35][36]
around
92%.
Some physicians and ethicists are
concerned about the ethical
[37]
ramifications of
this.
Conservative commentator
George Will
called it
eugenics
[38]
by abortion
British peer
Lord
Rix
stated that
Down's
syndrome is still considered by many to be an
utter tragedy
Sir Francis
Galton
, who founded the eugenics
movement in
[39]
1885, still
stalks the corridors of many a
teaching
hospital
Doctor David
Mortimer has argued in
Ethics & Medicine
that
[40]
been disparaged by some
doctors and government bean counters.
Some members of
the
disability
rights
movement
that
public
support
for
prenatal
diagnosis
and abortion based
on disability contravenes the movement's basic
philosophy and
[41]
goals.
Medical ethicist Ronald Green argues
that parents have an obligation to avoid
[42]
'genetic
harm'
to
their
offspring,
and
Claire
Rayner
,
then
a
patron
of
the
Down's
Syndrome
Association,
defended
testing
and
abortion
saying
hard
facts
are
that
it
is
costly
in
terms
of
human
effort,
compassion,
energy,
and
finite
resources
such
as
money, to
care
for
individuals with handicaps... People
who are not
yet parents
should ask themselves if they have the
right to inflict such burdens on others,
however willing they are themselves to
take their share of the burden in the
[43]
beginning.
Peter
Singer
argued
that
haemophilia
nor
Down's
syndrome
is
so crippling as to make
life not worth living, from the inner perspective
of the
person
with
the
condition.
To
abort
a
fetus
with
one
of
these
disabilities,
intending
to
have
another
child
who
will
not
be
disabled,
is
to
treat
fetuses
as
interchangeable
or
replaceable. If the mother has previously decided
to have a certain number of
children,
say two, then what she is doing, in effect, is
rejecting one potential
child in favour
of another. She could, in defence of her actions,
say: the loss of
life
of
the
aborted
fetus
is
outweighed
by
the
gain
of
a
better
life
for
the
normal
[44]
child who will be
conceived only if the disabled one
dies.
Management
Treatment
of
individuals
with
Down
Syndrome
depends
on
the
particular
manifestations
of the disorder. For instance,
individuals with congenital heart disease may need
to undergo major corrective surgery
soon after birth. Other individuals may have
relatively minor health problems
requiring no therapy.
Plastic surgery
Plastic surgery
has
sometimes been advocated and performed on children
with Down
syndrome, based on the
assumption that surgery can reduce the facial
features
associated with Down syndrome,
therefore decreasing social stigma, and leading to
[45]
a better quality of
life.
Plastic surgery on children with
Down syndrome is
[46]
uncommon,
and
continues to be controversial. Researchers have
found that for
facial
reconstruction
,
child's
speech and appearance, independent raters could
not readily discern
[47]
impr
ovement....
For
partial
glossectomy
(tongue
reduction),
one
researcher
found
that
1
out
of
3
patients
oral
competence,
with
2
out
of
3
showing
speech
[48]
improvement.
Len
Leshin,
physician
and
author
of
the
ds-health
website
,
has
stated,
being
in
use
for
over
twenty
years,
there
is
still
not
a
lot
of
solid
evidence
[49]
in
favor
of
the
use
of
plastic
surgery
in
children
with
Down
syndrome.
The
National
Down
Syndrome Society
has issued a
[50]
Children with Down
Syndrome
which states that
acceptance is mutual respect based on
who we are as individuals, not how we
look.
Alternative treatment
See also:
Alternative
therapies for developmental and learning
disabilities
The
Institutes
for
the
Achievement
of
Human
Potential
is
a
non-profit
organization
which treats
children who have, as the IAHP terms it,
including
children
with
Down
syndrome.
The
approach
of
Patterning
is
[51]
not proven,
and is considered
alternative
medicine
.
Role of the
professional social worker
Professional social workers have a
strong tradition of working for
social
justice
and refusing to
recreate unequal social structures. This means
going beyond state
sponsored practices
which merely cater to individual needs. Social
work maintains
this radical kernel with
the objective of transforming society as a whole.
Today
many social workers
internationally have strong connections with
social and
political movements for the
emancipation of the oppressed.