BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS 226, 226–230 (1996) ARTICLE NO. 1337 Protoporphyrinogen Oxidase: Complete Genomic Sequence and Polymorphisms in the Human Gene 1 Herve ´ Puy, Anne-Marie Robre ´au, Robert Rosipal, 2 Yves Nordmann, 3 and Jean-Charles Deybach Centre Franc ¸ais des Porphyries, INSERM U409, Ho ˆpital Louis Mourier, 92701 Colombes Cedex, France Received July 24, 1996 Variegate porphyria (VP) is an autosomal dominant disorder of heme synthesis caused by a partial deficiency of protoporphyrinogen oxidase (PPOX). Human cDNA encoding PPOX has been recently se- quenced and the gene has been cloned, assigned to chromosome 1q23, and its exon/intron organization has been characterized. We report here the complete nucleotide sequence of the Human PPOX gene. Including 660 bp of its promotor region, the PPOX gene spans 5.5 kb. Introns vary in size from 84 bp to 507 bp. Two exonic and 3 intronic biallelic sequence variations have been characterized.  1996 Academic Press, Inc. The enzyme protoporphyrinogen oxidase (PPOX; EC 1.3.3.4) acts at the penultimate step in the heme biosynthetic pathway, and catalyzes the oxidation of protoporphyrinogen IX to protoporphyrin IX within the inner mitochondrial membrane (1, 2). A partial deficiency of PPOX activity is responsible for variegate porphyria (VP), an autosomal dominant disease with incomplete penetrance (3-4). Clinical features of VP include both chronic photodermatitis and intermittent neurovisceral episodes which resemble those found in other acute hepatic porphyrias, acute intermittent porphyria and hereditary coproporphyria (2). Recently, Human PPOX cDNA has been cloned, sequenced and expressed (5-6). It consists of an open reading frame 1431 nucleotides long, encoding a 477 amino-acid protein. The gene has been mapped by FISH to chromosome 1q23, in contrast with a previous linkage assignment on chromosome 14 (7-9). The PPOX gene contains 13 exons and all exon/intron boundaries have been characterized 8 bp upstream and downstream of each exon (7-8). However, a discrepancy about the size of the gene still exists between Taketani et al. (7) and Roberts et al. (8) who respectively estimate the gene to span about 8 kb and 4.5 kb. In the present study, we describe the complete genomic sequence of the Human PPOX gene and report five intragenic dimorphisms. MATERIALS AND METHODS Subjects. Peripheral blood was collected from 50 unrelated control subjects of French Caucasian origin. Genomic DNA was extracted from peripheral blood as previously described (10). DNA sequencing. Oligonucleotides used were obtained from Genset (Paris, France). The regions corresponding to 1 The nucleotide sequence data reported in this paper will appear in the EMBL, GenBank and DDBJ Nucleotide Sequence Databases. 2 Cooperation: Universite ´ Paris VII, France – Univerzita Karlova, Praha, Czech Republic. 3 To whom correspondence should be addressed: Pr Y. Nordmann, Ho ˆpital Louis Mourier, 92701 Colombes Cedex, France. Fax : (33) 1 47 60 67 03. Abbreviations: PPOX, Protoporphyrinogen oxidase; VP, Variegate porphyria. 0006-291X/96 $18.00 Copyright  1996 by Academic Press, Inc. All rights of reproduction in any form reserved. 226