For instance, Iossifova et al. (2007, 2009), in prospective data, identified nonmonotonic relationships between (1→3)-β-d-glucans in dust and recurrent wheeze, wheeze with atopy, and an index for future asthma: Risks increased at increasing low concentrations, reached a maximum at 60 μg/g dust, and then decreased at increasing high concentrations. The gene discussed is PPIB; the disease is asthma.