Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0000737 (abdominal pain)
 31,184 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Variegate porphyria (VP), a low-penetrant autosomal dominant inherited disorder of haem metabolism, is characterised by photosensitivity (Fig. 1) and a propensity to develop acute neuropsychiatric attacks with abdominal pain, vomiting, constipation, tachycardia, hypertension, psychiatric symptoms and, in the worst cases, quadriplegia. Acute attacks, often precipitated by inappropriate drug therapy, are potentially fatal. While earlier workers thought the distal haem biosynthetic enzyme ferrochelatase may be involved in the genesis of VP, it was shown in the early 1980's, and is now accepted, that VP is associated with decreased protoporphyrinogen oxidase activity (PPO) (E.C.1.3.3.4). VP prevalence is much higher in South Africa than elsewhere; probably due to a founder effect with patients descending from a 17th century Dutch immigrant. PPO cDNAs from Bacillus subtilis, Myxococcus xanthus, human placenta and mouse liver have been cloned, sequenced and expressed. Human and mouse cDNAs consist of open reading frames 1431 nucleotides long, encoding a 477 amino acid protein. The human PPO gene contains thirteen exons, spanning approximately 4.5 kb. We have identified a C to T transition in codon 59 (in exon 3) resulting in an arginine to tryptophan substitution (R59W). A protein expressed from an in vitro-mutagenized PPO construct exhibits substantially less activity than the wild type. The R59W mutation was present in 43 of 45 patients with VP from 26 of 27 South African families investigated, but not in 34 unaffected relatives or 9 unrelated British patients with PPO deficiency. Since at least one of these families is descended from the founder of South African VP, this defect may represent the founder gene defect associated causally with VP in South Africa.
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PMID:A R59W mutation in human protoporphyrinogen oxidase results in decreased enzyme activity and is prevalent in South Africans with variegate porphyria. 867 6

A patient, who presented with abdominal pain and severe photosensitivity that resulted in scarring and mutilation of the fingers, nose and ears, was referred for biochemical assessment of porphyria and DNA screening. Although these clinical manifestations were suggestive of both acute porphyria and congenital erythropoietic porphyria, the biochemical profile was consistent with variegate porphyria (VP). Analysis of the protoporphyrinogen oxidase (PPOX) gene underlying VP resulted in the identification of the founder mutation R59W in a heterozygous state in this patient. Despite extensive mutation analysis, no other potential disease-causing genetic alterations could be detected in the PPOX gene or the uroporphyrinogen III synthase gene. Slight overrepresentation of the mutant PPOX allele was however, observed repeatedly in DNA of the proband compared to other R59W heterozygotes, including his mother who also tested positive for mutation R59W using restriction enzyme analysis and direct DNA sequencing. Confirmation of this phenomenon by real-time polymerase chain reaction analysis and microsatellite analysis, using highly informative markers flanking the PPOX gene, raised the possibility of partial homozygosity for VP in this patient. This study represents the first report of overrepresentation of mutation R59W in a patient with a severe form of VP. A homozygote for the R59W mutation has never been detected, and the severe clinical manifestation observed in our patient is consistent with the hypothesis that such a genotype will not be compatible with life.
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PMID:Overrepresentation of the founder PPOX gene mutation R59W in a South African patient with severe clinical manifestation of porphyria. 1566 Sep 19