Algorithm for distinguishing chronic blistering cutaneous porphyrias

This algorithm outlines an approach to the patient with suspected cutaneous porphyria and chronic blistering photosensitivity. Increased porphyrins in chronic blistering porphyrias are generally very elevated (eg, 10 times the upper limit of normal). Fractionation of porphyrins is accompanied by determination of the plasma fluorescence peak wavelength at neutral pH. Separate algorithms are available for the patient with suspected cutaneous porphyria with acute nonblistering photosensitivity and the patient with suspected acute (neurovisceral) porphyria. Refer to UpToDate topics on individual porphyrias for further discussions of the clinical manifestations and diagnostic evaluation.

PCT: porphyria cutanea tarda; HCP: hereditary coproporphyria; VP: variegate porphyria; CEP: congenital erythropoietic porphyria; HEP: hepatoerythropoietic porphyria; ALA: delta-aminolevulinic acid; PBG: porphobilinogen; UROD: uroporphyrinogen decarboxylase; CPOX: coproporphyrinogen oxidase; PPOX: protoporphyrin oxidase; UROS: uroporphyrinogen III synthase.
* We perform gene sequencing of the relevant gene for all cutaneous porphyrias diagnosed biochemically; this may be used for further confirmation of the diagnosis, identification of new mutations, and genetic counseling. For PCT, UROD gene sequencing often does not reveal a mutation; the presence of a heterozygous UROD mutation is consistent with familial (type 2) PCT. For other biochemically proven cases of porphyria, mutation of the associated gene is expected, and if no mutation is identified, this suggests mutation in a cryptic site, noncoding region, or regulatory gene.

Graphic 89035 Version 6.0

خرید پکیج

Algorithm for distinguishing chronic blistering cutaneous porphyrias