Abstract: This article reports the results of HLA antigen distribution in 23 families with multiple affected siblings alld 59 unrelated patients with psoriasis vulgaris. The frequency of HLA-A19, B13 and DR7 was significantly higher(Pc<0.001) than that of controls. It seems that the lower frequency of C7 and DQ1 is resistant to the development of psoriasis. Fifty-five health siblings in 23 families were observed for six to eight years. 20 out of 55 siblings had one or two same HLA haplotypes. Among the 20 persons, 4 siblings had psoriasis vulgaris,35 out of 55 siblings had no similar HLA haplotype and have not affected with psoriasis vulgaris up to now. It shows that HLA haplotype determination is helpful for the clinical surveillance of their healthy sibling with susceptible haplotype.

Key words: Psoriasis, Susceptible haplotype, Polygenic inheritance