Down’s syndromeA chromosomal ab-
normalityresulting in a variable degree
of learning difficultiesand a character-
istic physical appearance.
People with Down’s syndrome have an
extra chromosome (47 instead of 46).
Affected individuals have 3 copies of
chromosome number 21 instead of 2;
the disorder is also called trisomy 21. In
most cases, it is the result of a sperm or
egg being formed with an extra chromo-
some21. If one of these takes part in
fertilization, the baby will also have the
extra chromosome. This type of abnor-
mality is more likely if the mother is
aged over 35. A less common cause is
a chromosomal abnormality known as a
translocation, in which part of 1 parent’s
own chromosome number 21 has
joined with another chromosome. The
parent is unaffected but has a high risk
of having Down’s children.
Typical physical features of a person
with Down’s syndrome include small face
and features; sloping eyes with folds of
skin that cover their inner corners; large
tongue; and short, broad hands. People
with Down’s syndrome have a greater than
normal risk for certain disorders, such as
a heart defect at birth (see heart disease,
congenital), intestinal atresia(a narrowing
in the intestines), congenital deafness,
and acute leukaemia. Down’s syndrome
children are especially susceptible to
ear infections. A type of Alzheimer's dis-
easeoften develops after age 40.
Down’s syndrome is usually recog-
nized soon after birth. The diagnosis is
confirmed by chromosome analysis.
Screening tests during early pregnancy,
including ultrasound scanning, indicate
those fetuses likely to have the syn-
drome. Amniocentesisis then offered.
doxazosinAn antihypertensive drug taken
to reduce high blood pressure (see
hypertension). Side effects include dizzi-
ness, headache, and nausea.
doxorubicinAn anticancer druggiven
by injection, often with other anticancer
drugs. It is used to treat a variety of can-
cers, including lung cancer.
doxycyclineA tetracycline drugused in
the treatment of chronic prostatitis, pelvic
inflammatory disease, and chest infection
in chronic bronchitis. It is also used to
prevent and treat malaria. Taking the drug
with food reduces possible side effects.
DPT vaccination Also known as triple
vaccine, an injection that provides
immunity against diphtheria, pertussis
(whooping cough), and tetanus; The vac-
cine causes the body to produce
antibodiesagainst these infections. It is
given as a course of 3 injections at 2, 3,
and 4 months, followed by a preschool
booster dose. Before leaving school, a
further diphtheria and tetanus booster
is given. The vaccine does not provide
complete immunity to diphtheria or per-
tussis but reduces risk of serious illness.
Protection against pertussis and tetanus
gradually wanes. In adults, pertussis is
mild but can be transmitted to children.
Since tetanus is serious at any age, boost-
ers are recommended at the time of any
dirty, penetrating injury if there has not
been a vaccination in the past 10 years.
Reactions to the diphtheria and tetanus
parts of the vaccine are rare. The pertus-
sis vaccine often causes slight fever and
irritability for a day or so. More serious
reactions are extremely rare and include
seizures and an allergic reaction, which
may lead to sudden breathing difficulty
and shock. Permanent damage from the
vaccine is even rarer. Doctors are now
agreed that for most children, the bene-
fits of DPT outweigh the minimal risk
from the vaccine. The pertussis element
of the vaccine should not be given to
children who have reacted severely to a
preceding dose of the vaccine, or who
have a progressing brain abnormality.
drain, surgicalAn appliance inserted
into a body cavity or wound to release air
or to permit drainage. Drains range from
simple soft rubber tubes that pass from a
body cavity into a dressing to wide-bore
tubes that connect to a collection bag or
bottle. Suction drains are thin tubes with
many small holes to help collect fluid or
air, which is drawn into a vacuum bottle.
dream analysisThe interpretation of a
person’s dreams as part of psychoanalysis
or psychotherapy. First developed by Sig-
mund Freud, it is based on the idea that
repressed feelings and thoughts are re-
vealed, in a disguised manner, in dreams.
dreamingMental activity that takes
place during sleep. It is thought to occurDOWN’S SYNDROME DREAMING
D