Abstract: Li Changxing*, Li Xuemei, Zhang Xibao, Han Chunlei, Ma Zelin. *Department of Dermatology, Dongguan Municipal Hospital for Chronic Disease Prevention and Control, Dongguan 523008, Guangdong, China Corresponding author: Zhang Xibao, Email: zxibao@126.com 【Abstract】 Objective To detect mutations in the filaggrin （FLG） gene and expressions of FLG and loricrin in patients with ichthyosis vulgaris （IV）, and to investigate their clinical significance. Methods Tissue specimens were resected from the skin lesions of 10 patients with IV and normal skin of 14 healthy human controls, and immunohistochemical SP method was used to detect the expressions of filaggrin and loricrin. The expression intensity was determined by the Image-Pro Plus （IPP） software, and expressed as positive units （PU）. Blood samples were collected from 10 patients of Han nationality with IV and 100 healthy human controls followed by DNA extraction. PCR and DNA sequencing were performed to detect the presence of 13 mutations （3321delA, 441delA, 1249insG, E1795X, S3296X, R501X, 2282del4, R2447X, S2889X, 7945delA, 3702delG, Q2417X, R4307X） in the FLG gene. Results FLG was mainly expressed in the cytoplasm of keratinocytes in the stratum corneum, granular layer, prickle layer and basal layer, and loricrin was observed in the cytoplasm and nuclei of keratinocytes in the granular layer, prickle layer and basal layer, in both the lesional and normal skin. Compared with the normal skin, the lesional skin showed significantly weaker expressions of FLG （0.208 2 ± 0.008 0 vs. 0.230 0 ± 0.0228, t = 3.30, P < 0.01） and loricrin （0.137 0 ± 0.011 2 vs. 0.149 3 ± 0.007 3, t = 3.07, P < 0.01）. Sequencing analysis identified two mutations, including 3321delA in 7 patients and 441delA in 2 patients. No mutations were detected in the healthy controls. Conclusions The 3321delA and 441delA mutations in the FLG gene may represent the most frequent genetic cause of IV in patients of Han nationality. The low expressions of FLG and loricrin may be associated with the impairment of skin barrier function in patients with IV.

Key words: Ichthyosis vulgaris, Mutation, Filaggrin, Loricrin