ABSTRACT
<p><b>OBJECTIVE</b>To explore the possible genetic model of psoriasis vulgaris.</p><p><b>METHODS</b>The complex segregation analysis and heritability calculation were performed with the aid of Penrose method, Falconer regression method and SAGE-REGTL program.</p><p><b>RESULTS</b>It was found that in 1043 patients with psoriasis vulgaris, 305 patients (29.24%) have the family history of psoriasis, and 738 patients have not the family history. A ratio of s/q approached 1/(square root of q) with Penrose method, and the heritability values of psoriasis in the first-degree and second-degree relatives were 67.04%, 46.6% respectively. By complex segregation analysis, Mendelian, non-major-gene model and environment model were rejected for psoriasis.</p><p><b>CONCLUSION</b>The results suggest that psoriasis follows a pattern of polygenetic or multifactorial inheritance rather than single-gene inheritance.</p>