Recurrent missense mutation in the protoporphyrinogen oxidase gene underlies variegate porphyria

• Published in: American journal of medical genetics Vol. 79; no. 1; pp. 22 - 26
• Main Authors: Frank, Jorge, Jugert, Frank K., Breitkopf, Claudia, Goerz, Günter, Merk, Hans F., Christiano, Angela M.
• Format: Journal Article
• Language: English
• Published: New York John Wiley & Sons, Inc 27-08-1998; Wiley-Liss
• Subjects: Adult; Animals; Biological and medical sciences; Female; Flavoproteins; genodermatosis; Humans; Male; Medical sciences; Metabolic diseases; Mice; Middle Aged; Mitochondrial Proteins; Mutation; Other metabolic disorders; Oxidoreductases - genetics; Oxidoreductases Acting on CH-CH Group Donors; Pedigree; Pigments (porphyrias, hyperbilirubinemias...); Porphyrias, Hepatic - enzymology; Porphyrias, Hepatic - genetics; porphyrin-heme biosynthetic pathway; Protoporphyrinogen Oxidase; Recurrence; variegate porphyria; Human; Photosensitivity; Skin disease; Enzyme; Family study; Chromosome A1; Metabolic diseases; Genetic determinism; Porphyria variegata; Genetic disease; Missense mutation; Gene; Protoporphyrinogen oxidase; Pigments; Oxidoreductases
• ISSN: 0148-7299; 1096-8628
• DOI: 10.1002/(SICI)1096-8628(19980827)79:1<22::AID-AJMG6>3.0.CO;2-K

The porphyrias represent a heterogeneous group of disorders of porphyrin or porphyrin‐precursor metabolism, resulting from the inherited or acquired dysregulation of one of the eight enzymes in the porphyrin‐heme biosynthetic pathway. Variegate porphyria, one of the acute hepatic porphyrias, is characterized by a partial reduction in the activity of the penultimate enzyme in the heme biosynthetic pathway, protoporphyrinogen oxidase (PPO). Recently, VP has been linked to the PPO gene on chromosome 1q22−23, and several disease‐causing mutations have been described. In this study, we identified the underlying genetic lesion in two unrelated patients with VP and investigated all available family members by polymerase chain reaction, heteroduplex analysis, automated sequencing, and restriction enzyme digestion. Mutation analyses in both families revealed a G‐to‐A transition in exon 6 of the PPO gene resulting in the substitution of arginine by histidine at position 168 of the protein (R168H). This arginine residue is evolutionarily conserved in human, mouse, and Bacillus subtilis, indicating the importance of this residue in PPO function. Our study establishes a recurrent missense mutation as the underlying genetic defect in two unrelated patients with VP and explains the occurrence of the phenotype in their families. Am. J. Med. Genet. 79:22–26, 1998. © 1998 Wiley‐Liss, Inc.