Filaggrin Mutation c.3321delA in a Korean Patient with Ichthyosis Vulgaris and Atopic Dermatitis

the filaggrin gene (FLG) . The homozygous or compound heterozygous loss-of-function mutations p.R501X and c.2282del4 in FLG have been identified in moderate or severe IV patients from Ireland, Scotland and the USA [1] . These variants are carried by approximately 9% of European people and were also revealed to be important predisposing factors for AD [2] . Meanwhile, c.3321delA and p.S2554X mutations in FLG were identified as prevalent in Japanese IV and AD patients [3] . However, in that study the frequency of FLG mutations in the Japanese AD cohort was much lower than that seen in Europeans (5.6 and 48%, respectively) [3] . Recently, the same research group has reported additional nonsense FLG mutations (p.S2889X and p.S3296X) in Japan and extended the statistical significance of FLG null mutations in Japanese cases to 1 20% [4] . These findings imply that FLG mutations are predisposing factors for IV and AD, and show the presence of population-specific recurrent FLG mutations. In this regard, we analyzed FLG mutations in a 35-year-old Korean man who presented with a history of IV and AD since childhood. His sister and 2 daughters were affected by AD and xerosis. Marked adherent fine scales were clearly visible on his trunk. He also showed hyperlinear palms ( fig. 1 a, b). Histology revealed no keratohyalin granules in the granular layer ( fig. 2 ). We performed direct sequencing of the FLG gene in this patient, as well as screening for the previously reported mutations. Analysis revealed that he was a heterozygous carrier of the FLG mutation c.3321delA ( fig. 3 ). This mutation has already been reported by Nomura et al. [3] in Japanese cases.