Hydroa vacciniforme (HV) is a rare, chronic photosensitivity disorder commonly occurring in children. The disease is characterised by the eruption of inflamed bumps and fluid-filled blisters (vesicles) on the skin following exposure to sunlight. Commonly presenting on the face, ears and hands, these vesicles heal over time as pox-like or “vacciniform” scars.


Also known as PLE, PME or PMLE, Polymorphic Light Eruption is the most common skin disorder characterized by photosensitivity and, after sunburn, is the most common sun-related problem seen by doctors. PLE is a recurrent abnormal reaction to sunlight (or artificial ultraviolet radiation). It occurs after a delay on areas of the skin not regularly exposed, such as cleavage, upper arms, and trunk following sun exposure.


Xeroderma Pigmentosum (XP) is a rare, hereditary disease where patients experience skin hypersensitivity to ultraviolet (UV) light. It is characterized by dry skin, increased freckling as well as patches of hypo pigmentation and signs of premature aging. Affected individuals are particularly susceptible to developing actinic keratoses and squamous and basal cell carcinomas due to a defect in or lack of nucleotide excision repair (NER).


Porphyria cutanea tarda (PCT) is the most frequently seen disease of a group of disorders (the Porphyrias) that can be acquired or inherited. It is caused by low levels of an enzyme (uroporphyrinogen decarboxylase or UROD) involved in the production of haem (heme). Haem is a component of hemoglobin in red blood cells and is vital as it needs it to carry oxygen around the body. These result in a build-up of chemicals called porphyrins. In PCT, porphyrins accumulate in the skin, causing the skin to be very sensitive to light (photosensitive).


Erythropoietic protoporphyria (EPP) is a rare inherited metabolic disorder of the haem (heme) pathway causing severe phototoxicity (toxic reactions to light) in skin due to the build up of a phototoxic chemical in the skin. EPP belongs to a heterogenous group of disorders (porphyrias) that result from a dysfunction of specific enzymes involved in the haem biosynthesis. Haem serves many essential functions in the body one of which is oxygen transport via haemoglobin.


Solar urticaria (SU) is a rare, sunlight or UV induced hypersensitivity (allergic) reaction that causes wheals (raised red skin welts) very soon after or during sun or light exposure. In solar urticaria, the reaction is triggered by exposure to UV or visible light. It may be severely disabling and can even be life threatening.


Congenital erythropoietic porphyria, or CEP, is an extremely rare, inherited metabolic disorder.  It is caused by genetic defects which lead to deficiency of the enzyme uroporphyrinogen III cosynthase (UROS).  The disease is characterised by extreme photosensitivity (abnormal cutaneous reaction to sunlight) which can leave severe scarring, blister formation and the loss of digits or other features.


ariegate porphyria (VP) is a rare autosomal dominant inherited disorder resulting from the deficiency of the mitochondrial enzyme protoporphyrinogen oxidase (PPOX), the sixth enzyme of the haem biosynthesis pathway. A debilitating and burdensome disease for patients, VP is classified as both a cutaneous and acute porphyria.