Diseases associated with photosensitivity.

Photosensitive disorders may be classified as those entirely caused by solar exposure and the photoaggravated disorders. Those in the former category include polymorphic light eruption, juvenile spring eruption, actinic prurigo, hydroa vacciniforme, solar urticaria, also chronic actinic dermatitis. Genodermatoses whose expression mainly depends on UV or light exposure include the DNA repair deficient disorders, some disorders of cornification, the Smith-Lemli-Opitz syndrome and porphyria. Examples of photoaggravated diseases include lupus erythematosus, erythema multiforme, atopic eczema, psoriasis, viral exanthemata, pemphigus, dermatitis herpetiformis and rosacea. Drugs and chemicals may interact with UV to induce photosensitivity. In many of these diseases the action spectrum is known or may be determined by phototesting. Recognition of the reaction patterns associated with the photodermatoses greatly assists clinical classification of the photodermatoses.

Successful therapeutic effect in a mouse model of erythropoietic protoporphyria by partial genetic correction and fluorescence-based selection of hematopoietic cells.

Erythropoietic protoporphyria is characterized clinically by skin photosensitivity and biochemically by a ferrochelatase deficiency resulting in an excessive accumulation of photoreactive protoporphyrin in erythrocytes, plasma and other organs. The availability of the Fech(m1Pas)/Fech(m1Pas) murine model allowed us to test a gene therapy protocol to correct the porphyric phenotype. Gene therapy was performed by ex vivo transfer of human ferrochelatase cDNA with a retroviral vector to deficient hematopoietic cells, followed by re-injection of the transduced cells with or without selection in the porphyric mouse. Genetically corrected cells were separated by FACS from deficient ones by the absence of fluorescence when illuminated under ultraviolet light. Five months after transplantation, the number of fluorescent erythrocytes decreased from 61% (EPP mice) to 19% for EPP mice engrafted with low fluorescent selected BM cells. Absence of skin photosensitivity was observed in mice with less than 20% of fluorescent RBC. A partial phenotypic correction was found for animals with 20 to 40% of fluorescent RBC. In conclusion, a partial correction of bone marrow cells is sufficient to reverse the porphyric phenotype and restore normal hematopoiesis. This selection system represents a rapid and efficient procedure and an excellent alternative to the use of potentially harmful gene markers in retroviral vectors.

Long-term follow-up after liver transplantation for erythropoietic protoporphyria.

OBJECTIVE: Erythropoietic protoporphyria (EPP) is an inherited disorder of haem synthesis, causing excess of protoporphyrin in blood, skin, liver and other organs. Protoporphyrin causes rapidly progressive liver failure in a minority of EPP patients. Long-term follow-up after liver transplantation for EPP is poorly documented. DESIGN: Two EPP patients were followed for 7 years after liver transplantation. Porphyrin levels were monitored and serial liver biopsies were taken. RESULTS: After transplantation, serum protoporphyrin levels remained elevated. In one patient, long periods with normal liver tests, low protoporphyrin levels and the absence of photosensitivity were followed by episodes of cholestasis and elevated protoporphyrin levels in blood, faeces and liver tissue. These episodes could be managed successfully with blood transfusions and changes in medication. The simultaneous rise of protoporphyrin concentration in both blood and faeces in this patient argues for increased protoporphyrin production as the cause of liver cell injury. The other patient acquired hepatitis B infection during the transplantation. From 3 months onwards she had continuously elevated liver tests, cholestasis, elevated protoporphyrin levels in blood, faeces and liver tissue, and photosensitivity. In this case, cholestasis and impaired protoporphyrin excretion may have played an important role in the persistent liver injury. Sequential liver biopsies of both patients showed various degrees of liver injury related to variations of the hepatic protoporphyrin concentrations. Eight and six months respectively after liver transplantation the livers of both patients showed fibrosis and hepatocellular protoporphyrin accumulation. CONCLUSIONS: The main cause of liver damage in EPP is overproduction of protoporphyrin in the bone marrow. Liver transplantation must be considered as symptomatic therapy with a high-risk for recurrent disease.