Allergy and asthma are closely related conditions which result from a compl
ex interaction between several genetic and environmental factors. On the ba
sis of familial link-age analysis data from different populations, some chr
omosomal regions containing a series of susceptibility loci have been ident
ified. To date, genome-wide search studies have reported a group of chromos
omal regions which include most likely several candidate genes for asthma a
nd allergy. Some of these genes are excellent candidates, as they are known
to modulate the immune response and airways inflammation processes, So, by
focusing efforts on the analysis of those chromosomal regions, the charact
erization of the potentially important genes can be achieved. This will und
oubtedly provide a clue for a better understanding of those pathologic comp
onents involved in the onset and development of asthma and allergic disorde
rs.