The increasing prevalence of asthma in industrialized societies may be a consequence of improved hygiene levels and a reduction in the incidence in infections such as tuberculosis and hepatitis A. But, the molecular mechanisms that would help to explain these theories remain elusive. In November 28 Nature Immunology Jennifer McIntire and colleagues from Stanford University, Stanford, US show that Tim1 gene on chromosome 5q may explain the inverse relationship between hepatitis A virus (HAV) infection and reduced asthma susceptibility.

McIntire et al. used congenic inbred mouse strains (that differed only by a small chromosomal region) and found a Mendelian trait encoded by T cell and Airway Phenotype Regulator (Tapr) on chromosome 5q23-35. In addition, positional cloning identified variants of a gene that encodes T cell membrane proteins (TIMs) which completely cosegregated with Tapr (Nat Immunol 2001, 2:1109-1116).

Tapr controls the development of airway hyperreactivity and...

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