Bma Illustrated Medical Dictionary

clear up after taking a few deep breaths
or after resting for a short time. Severe,
prolonged, or recurrent dizziness should
be investigated by a doctor. Treatment
depends on the underlying cause.
DLEDiscoid lupus erythematosus.
DMSA scanA type of kidney imaging
technique (see radionuclide scanning).
DNAThe abbreviation for deoxyribo-
nucleic acid, the principal molecule
carrying genetic information in almost
all organisms; the exceptions are cer-
tain viruses that use RNA. DNA is found
in the chromosomesof cells; its double-
helix structure allows the chromosomes
to be copied exactly during the process
of cell division. (See also nucleic acids.)

DNA fingerprintingSee genetic fin-
gerprinting.
dogs, diseases fromInfectious or par-
asitic diseases that are acquired from
contact with dogs. They may be caused
by viruses, bacteria, fungi, protozoa,
worms, insects, or mites living in or on a
dog. Many parasites that live on dogs can
be transferred to humans. The most seri-
ous disease from dogs is rabies. The UK
is free of rabies, but travellers to coun-
tries in which rabies exists should treat
any bite with suspicion. Dog bites can
cause serious bleeding and shock and
may become infected. Toxocariasisand
hydatid diseaseare potentially serious
diseasescaused by the ingestion of
worm eggs from dogs. In the tropics,
walking barefoot on soil that is contam-
inated with dog faeces can lead to dog
hookworm infestation.

Bites from dog fleasare an occasional

nuisance. Ticksand mitesfrom dogs,

including a canine version of the scabies

mite, are other common problems. The

fungi that cause tineainfections in dogs

can be caught by humans.

Some people become allergic to ani-

mal dander(tiny scales from fur or

skin). They may, for example, have asth-

ma or urticaria when a dog is in the

house. (See also zoonoses.)

dominantA term used in geneticsto

describe one of the ways in which a gene

is passed from parent to offspring. Many

characteristics are determined by a single

pair of genes, 1 of each pair being inherit-

ed from each parent. A dominant gene

overrides an equivalent recessivegene.

For example, the gene for brown eye

colour is dominant, so if a child inherits

the gene for brown eyes from 1 parent

and the gene for blue eyes from the other,

he or she will have brown eyes. Some

genetic disorders are determined by a

dominant gene. Examples include Mar-

fan’s syndromeand Huntington’s disease.

The child will have the disease if he or she

inherits the gene from 1 or both parents.

domperidoneAn antiemetic drugused

to relieve nausea and vomiting associ-

ated with some gastrointestinal disorders

or during treatment with certain drugs or

radiotherapy. Adverse effects may in-

clude breast enlargement and secretion

of milk from the breast.

donorA person who provides blood for

transfusion, tissues or organs for trans-

plantation, eggs, or semen for artificial

insemination. The organs most frequently

donated are kidneys, corneas, heart,

lungs, liver, and pancreas. Certain organs

can be donated during a person’s life-

time; some are only used following brain

death. All donors should be free of can-

cer, serious infection (such as hepatitis

B), and should not carry HIV. Organs for

transplantation must be removed within

a few hours of brain death, and before or

immediately after the heartbeat has

stopped. In some kidney transplants, the

kidney is provided by a living donor,

usually a relative whose body tissues

match well on the basis of tissue-typing.

Suitable related donors may also pro-

vide bone marrow for transplantation

DLE DONOR

D

Chromosome

Gene

DNA helix

DNA