Flare-ups sometimes occur in the winter, as a result of dry skin and lack of sunlight. The disease is clearly a clinically and genetically heterogeneous disorder. Given the prevalence of psoriasis, it is not surprising that studies have found associations between this disease and more than one genetic locus. Good examples included the several studies of insulin-dependent diabetes mellitus patients in which more than 10 genetic loci have been identified. It is this genetic susceptibility in conjunction with environmental triggers which are thought to determine the clinical manifestation of psoriasis.
Psoriasis comes in many forms.
Each differs in how bad it is, how long it lasts, where it is and in the shape and pattern of scales. The most common form begins with little red bumps. Gradually these grow larger and scales below the surface stick together. When they are removed, the tender, exposed skin bleeds. These small red areas then grow, sometimes becoming quite large.