Homozygous variegate porphyria: identification of mutations on both alleles of the protoporphyrinogen oxidase gene in a severely affected proband.
Homozygous variegate porphyria is a severe skin and neurologic disease manifesting in early infancy, and characterized by markedly reduced levels of the penultimate enzyme in the heme biosynthetic pathway, protoporphyrinogen oxidase. We investigated the molecular basis of variegate porphyria, usually an autosomal dominantly inherited trait, in a severely affected female proband and her parents. The mutation detection strategy included heteroduplex analysis, automated sequencing, and allele specific oligonucleotide hybridization. We identified two underlying missense mutations in the protoporphyrinogen oxidase gene, consisting of a G-to-A transition in exon 6 (G169E), and a G-to-A transition in exon 10 (G358R). Our study establishes the molecular basis of "homozygous" variegate porphyria for the first time, in demonstrating that this patient is a compound heterozygote for two different missense mutations in the protoporphyrinogen oxidase gene.
Frank
J
J
Department of Dermatology, Columbia University, New York, New York 10032, USA.
McGrath
J
J
Lam
H
H
Graham
R M
RM
Hawk
J L
JL
Christiano
A M
AM
D000328:Adult; D000483:Alleles; D000595:Amino Acid Sequence; D001483:Base Sequence; D005091:Exons / Q000235:genetics; D005260:Female; D005420:Flavoproteins; D006720:Homozygote; D006801:Humans; D024101:Mitochondrial Proteins; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics*; D009692:Nucleic Acid Heteroduplexes / Q000235:genetics; D010088:Oxidoreductases / Q000235:genetics*; D044925:Oxidoreductases Acting on CH-CH Group Donors; D011164:Porphyrias / Q000235:genetics* / Q000503:physiopathology*; D050768:Protoporphyrinogen Oxidase
D005420:Flavoproteins; D024101:Mitochondrial Proteins; D009692:Nucleic Acid Heteroduplexes; D010088:Oxidoreductases; D044925:Oxidoreductases Acting on CH-CH Group Donors; C493978:PPOX protein, human; D050768:Protoporphyrinogen Oxidase