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ASTHMA
Asthma
affects more than 5% of the population of the
US, including children. It is a chronic inflammatory disorder of the
airways characterized by coughing, shortness of breath and chest
tightness. A variety of 'triggers' may initiate or worsen an asthma
attack, including viral respiratory infections, exercise and exposure to
irritants such as tobacco smoke. The physiological symptoms of asthma
are a narrowing of the airways caused by edema (fluid in the
intracellular tissue space) and the influx of inflammatory cells into
the walls of the airways.
Asthma is a what is known as a 'complex' heritable disease.
This means that there are a number of genes that contribute towards a
person's susceptibility to a disease, and in the case of asthma,
chromosomes 5, 6, 11, 14, and 12 have all been implicated. The relative
roles of these genes in asthma predisposition are not clear, but one of
the most promising sites for investigation is on chromosome 5. Although
a gene for asthma from this site has not yet been specifically
identified, it is known that this region is rich in genes coding for key
molecules in the inflammatory response seen in asthma, including
cytokines, growth factors, and growth factor receptors.
The search for specific asthma genes is ongoing. Assisting
in this international human effort are model organisms such as mice,
which have similar chromosomal architecture to our chromosome 5 site on
their chromosomes 11, 13 an 18. Further study of the genes in these
areas (and others) of the human genome will implicate specific genes
involved in asthma and perhaps also suggest related biological pathways
that play a role in the pathogenesis of asthma.
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