What is the role of genetic testing in the workup of porphyria?

Updated: Aug 31, 2020
  • Author: Brenda Chiang, DO; Chief Editor: Emmanuel C Besa, MD  more...
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Answer

Testing for genetic mutations is increasingly available for the diagnosis of porphyrias. Prenatal diagnosis is possible in some types of porphyria.

For example, in congenital erythropoietic porphyria, pink fluorescence of the amniotic fluid examined fortuitously in sunlight is suggestive. DNA analysis may show the mutation C73R in the gene for URO-synthase. [59] Another detectable mutation is PPOX, encoding the mitochondrial enzyme protoporphyrinogen oxidase in variegate porphyria. [20] Heterozygous mutation in CPOX (encoding coproporphyrinogen-III oxidase) confirms the diagnosis of hereditary coproporphyria. [60] However, the utility of prenatal testing is questionable as many heterozygous carriers live healthy lives. The prenatal testing thus should not be done unless pregnancy termination is being considered.

A mutation screening for family members should be conducted to identify symptom-free carriers, especially in cases with a positive family history. [37]


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