Department of Skin and Venereal Diseases, University of Ioannina Medical School, Ioannina, Greece.
Med Hypotheses. 2012 Jan;78(1):183-90. doi: 10.1016/j.mehy.2011.10.022. Epub 2011 Nov 12.
Psoriasis is a genetically determined, almost worldwide-distributed inflammatory skin disease with overall higher prevalence among people of northern European ancestry. Since enhanced innate immunity is an important feature of the pathophysiology of this disease, it has been proposed that differences in the prevalence of psoriasis in different populations mainly result from differences in natural selection for gene polymorphisms associated with more vigorous immunity against infectious agents. However the infectious agent(s) that could have acted upon human population as selection pressure for psoriasis is still obscure. Based on the remarkable clinical observation that psoriasis and leprosy are almost mutually exclusive, a fact that is further supported by divergent HLA patterns in patients with psoriasis and leprosy we propose that "resisting leprosy" may have been the evolutionary advantage that favoured the expansion of some psoriasis-associated genotypes especially in the progenitors of modern Europeans. Moreover, we suggest that the spreading out of a certain genetic resistance trait may offer a supplementary explanation for the better understanding of the relatively rapid decline of leprosy in the late medieval epoch in Europe. Both genetic and paleoepidemiologic methods could be employed in order to challenge the present hypothesis.
银屑病是一种遗传性的、几乎在全球范围内存在的炎症性皮肤病，在北欧血统人群中的发病率更高。由于先天免疫增强是这种疾病病理生理学的一个重要特征，因此有人提出，不同人群中银屑病的患病率差异主要是由于与针对传染性病原体的更强免疫力相关的基因多态性的自然选择差异所致。然而，作为银屑病选择压力的可能的传染因子仍然不清楚。基于银屑病和麻风病几乎完全相互排斥的显著临床观察，以及银屑病和麻风病患者 HLA 模式的差异进一步支持了这一事实，我们提出“抗麻风病”可能是有利于某些银屑病相关基因型扩展的进化优势，尤其是在现代欧洲人的祖先中。此外，我们认为，某种遗传抗性特征的传播可能为更好地理解欧洲中世纪后期麻风病的迅速减少提供了一个补充解释。可以采用遗传和古流行病学方法来挑战目前的假设。
