[The geographic distribution of psoriasis].

On the basis of data published in the literature the geographical distribution of psoriasis vulgaris is described. One of the most interesting results is the increase of the psoriasis frequency in countries such as Japan, Korea, Kazachstan and East Africa. This could be due to the fact, that altered life conditions in connection with an increasing industrialization favour the manifestation of psoriasis genes. How far population differences of the psoriasis frequencies are to be seen exclusively as genetical ones, is hitherto unclear, but rather unlikely. No relations between psoriasis and climatec factors could be seen. Associations between psoriasis and several antigens (HL-A 13 and W 17) of the HL-A-systems seem to be present. These associations could be of considerable importance for the interpretation of the geographical distribution pattern of psoriasis. Further studies in psoriatic families are required, which describe the distribution of the HL-A specifities in the possibly potential psoriatic members of the families, who carry the respective genes.