Suggestive evidence for genetic linkage between IgE phenotypes and chromosome 14q markers

Chromosome 14q was screened for loci modulating immunoglobulin E (IgE) phenotypes in 15 extended and 45 nuclear asthmatic families using a panel of 14 microsatellite markers. We examined the reported linkage between the TCR A/D locus on 14q11.2 and specific (cognate) allergic responses and observed supportive evidence for linkage between a general skin prick test reactivity trait (but not with total serum IgE) and TCRA microsatellite (in the total sample of informative sib-pairs p = 0.039, in selected sample of one or zero affected parent p = 0.017). We also show suggestive evidence for a novel linkage between markers D14S75 and D14S63 on 14q13-23 and log total serum IgE (p = 0.034 and p = 0.0029). The evidence for linkage with marker D14S63 on 14q23 is strengthened by the finding of association of allele 165 to log IgE (p = 0.0029). We conclude that chromosome 14q may contain a locus close to TCR A/D at 14q11.2 linked to skin prick reactivity and a locus at 14q13- 23 linked to total serum IgE.

Gastric asthma: an unrecognized disease with an unsuspected frequency

Bronchial asthma is a disease that has been recognized for centuries, which is influenced mainly by genetic and environmental factors. The current interest of bronchial asthma is focused to ascertain the causes and the mechanisms that induce bronchoconstriction. Recently, abnormalities of the esophageal and gastric tracts have become important related areas for research. In predisposed individuals, these abnormalities can trigger or worsen the particular syndrome better known as "gastric asthma." In bronchial asthma the disorder of gastroesophageal reflux (GER) occurs more often than would be expected by chance. The neurogenic mechanism is considered to be the main cause of bronchoconstriction. The diagnosis of gastric asthma is particularly difficult and it should be considered also when GER is less evident or not recognized. In asthmatic patients the recognition of gastric abnormalities is very relevant for therapeutic problems also when GER is in a subclinical stage. In fact, many drugs used in the treatment of bronchial asthma can promote or enhance GER and subsequently they can worsen the symptoms of gastric asthma.

Cutting Edge: Dominant Effect of Ile50Val Variant of the Human IL-4 Receptor α-Chain in IgE Synthesis

Two variants of the IL-4R α-chain (IL-4Rα) gene have been recently identified in association with different atopic disorders. To clarify the etiological relationship between the two variants, we analyzed responsiveness to IL-4 of transfectants with four kinds of IL-4Rα carrying either Val or Ile at 50 and either Gln or Arg at 551. The substitution of Ile for Val augmented STAT6 activation, proliferation, and transcription activity of the Iε promoter by IL-4, whereas that of Arg for Gln did not change these IL-4 signals. Arg551 was not associated with atopic asthma in the Japanese population. CD23 expression and IgE synthesis by IL-4 were augmented in Ile50-bearing PBMC, compared with those bearing Val50. Taken together, substitution of Arg551 does not enhance the IL-4 signal for generation of germline ε transcript, whereas the substitution of Ile50 contributes to enhancement of IgE synthesis.