Asthma is a condition which causes the
airways to narrow, often in response to
a "trigger" such as exposure to
something that causes an allergic
reaction - cold air, exercise, or
emotional stress. This narrowing causes
symptoms such as wheezing, shortness of
breath, chest tightness, and coughing,
which respond to drugs known as
bronchodilators. Between episodes, most
patients feel fine.
The disorder is a chronic (recurring)
condition in which the airways become
very sensitive to irritation. Asthma
causes inflammation, increased mucus
production, and intermittent airway
obstruction. The symptoms of asthma,
which can range from mild to life
threatening, can usually be controlled
with a combination of drugs and
lifestyle changes.
Public attention in the developed world
has recently focused on asthma because
it seems to be on the increase,
affecting up to one in four children
who live in cities.
Susceptibility to asthma can be
explained in part by genetic factors,
but no clear pattern of inheritance has
been found. Asthma is a complex disease
that is influenced by multiple genetic,
developmental, and environmental
factors, which interact to produce the
overall condition.



