The porphyrias, appropriate test selection.

Background: Clinical and biochemical diagnosis of the porphyrias is a difficult task and is currently based upon review of the clinical features and measurement of the various porphyrin metabolites in body fluids.

Materials: Different techniques are available for the diagnosis of the porphyrias and the identification of the eventual defect(s), ranging from simple biochemical measurement of aminolevulinic acid (ALA) and porphobilinogen (PBG) through enzymatic assays to the investigation of genetic abnormalities.

Results: Except for erythrocyte porphobilinogen deaminase, the use of porphyrin enzyme measurement is beyond the scope of most laboratories.

Single-strand conformational polymorphism and denaturing gradient gel electrophoresis in screening for variegate porphyria: identification of two new mutations.

Single-strand conformational polymorphism and denaturing gel electrophoresis were used to screen for mutations in the protoporphyrinogen oxidase gene (PPOX) of three patients with clinically and biochemically proven variegate porphyria in order to select genomic regions for specific DNA sequence analysis. Two previously undescribed mutations were identified: PPOX1423-1426-delATCT and PPOX2272insG. Denaturing gel electrophoresis was able to discern the point mutation in exon 5 (PPOX2272insG) of the PPOX gene.

Caveats in hair analysis in chronic arsenic poisoning.

The diagnosis and evaluation of chronic arsenic poisoning remains a difficult task. Clinical indicators are crude measures, and electromyography adds little to the picture. Blood arsenic levels are transitory, however urine levels are useful for monitoring ongoing exposure.