Comprehensive screening for a complete set of Japanese-population-specific filaggrin gene mutations

Mutations in FLG coding profilaggrin cause ichthyosis vulgaris and are an important predisposing factor for atopic dermatitis. Until now, most case-control studies and population-based screenings have been performed only for prevalent mutations. In this study, we established a high-throughput FLG mutation detection system by real-time PCR with a set of two double-dye probes and conducted comprehensive screening for almost all of the Japanese-population-specific FLG mutations (ten FLG mutations). The present comprehensive screening for all ten FLG mutations provided a more precise prevalence rate for FLG mutations (11.1%, n = 820), which seemed high compared with data of previous reports based on screening for limited numbers of FLG mutations. Our comprehensive screening suggested that population-specific FLG mutations may be a significant predisposing factor for hay fever (odds ratio = 2.01 [95% CI: 1.027-3.936, P < 0.05]), although the sample sizes of this study were too small for reliable subphenotype analysis on the association between FLG mutations and hay fever in the eczema patients and the noneczema individuals, and it is not clear whether the association between FLG mutations and hay fever is due to the close association between FLG mutations and hay fever patients with eczema.