[Progress in dermatology: new biochemical aspects].

Recent biochemical advances have contributed to clarification of certain skin diseases and metabolic disturbances with predominantly cutaneous symptoms. This is illustrated by the various forms of porphyria. Today we differentiate four hepatic forms: acute intermittent porphyria, variegate porphyria, hereditary coproporphyria and porphyria cutanea tarda, and two erythropoietic forms: congenital erythropoietic porphyria and erythropoietic protoporphyria, all of which are due to an inborn enzymatic deficiency of the heme biosynthesis. From the different forms of ichthyosis, the X-recessive ichthyosis has an underlying enzymatic deficiency of the steroid sulfatase, which seems of significance in the disturbance of keratinization. In epidermolysis bullosa dystrophica type Hallopeau-Siemens an increased collagenase activity was detected. Inhibition of this enzyme by phenytoin results in improvement of the blistering in this genodermatosis. The etiology and pathogenesis of psoriasis are unclear despite extensive efforts. The recently detected deficiency of the arylhydrocarbon-hydroxylase and its inducibility must be confirmed, additionally its significance in the pathogenesis of this disease is yet to be evaluated.