Background Recently, we have reported filaggrin mutations (FLG) of atopic dermatitis in southern China. However, there have been few detailed reports of FLG mutations of patients with AD in northern China by now.
Objectives The present aim was to establish the mutation spectrum of FLG gene in AD patients in northern China.
Methods A total of 339 cases met Hanifin and Rajka diagnostic criteria of AD were recruited. A comprehensive sequencing of the entire FLG coding region in these patients was conducted. All detected FLG null mutations were screened in a cohort of 301 normal controls.
Results Seven novel mutations (478insA, Q1070X, 4026delT, Q1712X, Q2397X, 7145del4 and 8001del4) and eleven reported mutations (3222del4, 3321delA, 4271delAA, S1515X, Q1790X, 5757del4, 6834del5, Q2417X, E2422X, 7945delA and K4671X) in AD were identified. Mutations 3321delA and K4671X were two of the most common mutations in AD. FLG null mutations were present in 26.0% of AD patients. FLG null alleles (compound genotypes) were significantly higher in AD (P < 0.001) than in the controls. The compound genotypes for all FLG variants were significantly associated with IV (P < 0.001) and palmar hyperlinearity (P < 0.001). The common mutation, K4671X, was significantly associated with AD-coexistent allergic rhinitis (P = 0.005).
Conclusions Our study increases the total number of FLG mutations. We clearly demonstrated that FLG loss-of-function mutations were significantly associated with AD in northern China. The FLG null mutations in the Chinese population differed not only from that in the European population but also from that in sub-populations of Asians outside of the Chinese mainland.