Novel FLG null mutations in Korean patients with atopic dermatitis and comparison of the mutational spectra in Asian populations

Filaggrin is essential for the development of the skin barrier. Mutations in the gene encoding filaggrin have been identified as major predisposing factors for atopic disorders. Molecular analysis of the FLG gene in this study showed nine null and one unclassified mutation in 13 of 81 Korean patients with atopic dermatitis (AD): five novel null mutations (i.e. p.S1405*, c.5671_5672delinsTA, p.W1947*, p.G2025* and p.E3070*); four reported null mutations (i.e. c.3321delA, p.S1515*, p.S3296* and p.K4022*); and one unclassified mutation (i.e. c.306delAAAGCACAG). These variants are nonsense, premature termination codon or in-frame deletion expected to cause loss-of-function of FLG. Genotype-phenotype correlation is not obvious in Korean AD patients with FLG null mutations. According to a review of the mutational spectra of the FLG gene in the Asian populations, FLG null mutations appeared to be unique in each population but some mutations such as p.R501*, c.3321delA, p.S1515*, p.S3296* and p.K4022* were commonly found in at least two of the selected Asian populations including Korean, Japanese, Chinese, Singaporean Chinese or Taiwanese. Further investigations on a larger group of Korean AD would be necessary to elucidate its clinical pathogenesis and mutational spectrum related to specific FLG null mutations for AD.