Affected sib-pair and mutation analyses of the high affinity IgE receptor beta chain locus in Italian families with atopic asthmatic children.

Previous studies reported linkage between maternally inherited atopy and the beta subunit of the high affinity IgE receptor (Fc epsilon RI-beta) located on chromosome 11q13. We have investigated 45 Italian families with atopic asthmatic children, for a total of 213 subjects, including 148 patients. Genotyping was carried out with two microsatellite DNA markers: one (Fc epsilon RI-beta CA) located inside the gene, and one (CI11-319 CA) closely linked to it. Affected sib-pair analysis in families with several affected children indicated 128 pairs in which either both markers were informative. An excess of maternal allele sharing was observed, although not significant. The allele-specific DNA amplification test for the FcRI-beta Ile181Leu mutation, described previously in 17% of atopic English families by Shirakawa and coworkers, was negative in all our families, as well as in 42 Italian children with atopic asthma and without family histories of the disease.