Latent class analysis of 146 adult patients with CF identified three distinct classes of aspergillosis: ABPA, patients with a positive PCR, elevated total and specific A. fumigatus IgE/IgG and a positive galactomannan; Aspergillus sensitized, patients with or without a positive PCR, elevated A. fumigatus IgE (not IgG) and a negative sputum galactomannan; Aspergillus bronchitis, patients with a positive PCR, elevated A. fumigatus IgG and a positive sputum galactomannan. The gene discussed is IGHE; the disease is aspergillosis.