1/37. Mutations in the translation initiation codon of the protoporphyrinogen oxidase gene underlie variegate porphyria. Variegate porphyria (VP), one of the acute hepatic porphyrias, is characterized by a reduced catalytic activity of protoporphyrinogen oxidase (PPO), the penultimate enzyme in the porphyrin-haem biosynthetic pathway. VP has been linked to the PPO gene on chromosome 1q22-23, and several mutations underlying this disorder have been described recently. In this study, we identified two different missense mutations in the translation initiation codon of the PPO gene in two unrelated patients with VP. mutation analysis was carried out using PCR, heteroduplex analysis, automated sequencing, and restriction enzyme digestion. In the first patient, the results revealed an A-to-T transversion (ATG --> TTG), resulting in the substitution of methionine by leucine (M1L). The mutation detected in the second patient was a T-to-C transition (ATG --> ACG), leading to the conversion of methionine to threonine (M1T). These mutations abolish the initiation of translation at the normal site, and consequently, translation of an abnormal messenger rna (mRNA) would result in the synthesis of a truncated PPO protein lacking the amino terminus. ( info) |
2/37. Novel molecular defects of the delta-aminolevulinate dehydratase gene in a patient with inherited acute hepatic porphyria. Cloning and expression of the defective gene for delta-aminolevulinate dehydratase (ALAD) from the second of 2 German patients with ALAD deficiency porphyria (ADP), who had been originally reported by Doss et al. in 1979, were performed. Cloning of cDNAs for the defective ALAD were performed using Epstein-Barr virus (EBV)-transformed lymphoblastoid cells of the proband, and nucleotide sequences of cloned cDNA were determined. Two separate mutations of ALAD cDNA were identified in each ALAD allele. One was G457A, termed "H1," resulting in V153M substitution, while the other was a deletion of 2 sequential bases at T(818) and C(819), termed "H2," resulting in a frame shift with a premature stop codon at the amino acid position of 294. Using allele-specific oligonucleotide hybridization, the mother of the proband was shown to have an H1 defect, while using genomic dna analysis, the father was shown to have an H2 defect. Expression of H1 cDNA in Chinese hamster ovary cells produced an ALAD protein with only a partial activity (10.65% /- 1.80% of the normal), while H2 cDNA encoded no significant protein. These data thus demonstrate that the proband was associated with 2 novel molecular defects of the ALAD gene, 1 in each allele, and account for the extremely low ALAD activity in his erythrocytes ( approximately 1% of normal). ( info) |
3/37. Homozygous variegate porphyria in south africa: genotypic analysis in two cases. Variegate porphyria is an autosomal dominant disorder of heme metabolism which results from decreased activity of the enzyme protoporphyrinogen oxidase. Clinically, the disease manifests postpubertally and is characterized by photocutaneous sensitivity and/or acute neurovisceral crises. However, in homozygous variegate porphyria, onset of the disease usually occurs in infancy with severe skin manifestations. The molecular basis of variegate porphyria in two severely affected probands in two South African families is described. mutation detection included combined SSCP-heteroduplex analysis followed by direct sequencing. The unrelated probands both had the common R59W mutation while the other lesion was Y348C or R138P (both novel mutations), causing homozygous variegate porphyria. ( info) |
4/37. Acute porphyric disorders. Acute porphyrias are classified into 3 distinct groups of rare genetic disorders of metabolic enzyme biosynthesis. Acute porphyrias can significantly impact multiple organ systems, which often provides a challenge to the dentist presented with such a patient. A case of hereditary coproporphyria is reported in a patient with many of the classical signs and symptoms. The patient also had complex dental needs that required special medical and pharmacotherapeutic modifications. The acute porphyrias are reviewed by the authors with presentation of this challenging case. Recommendations for other dental health care professionals encountering these patients are then presented. ( info) |
5/37. Homozygous variegate porphyria: a compound heterozygote with novel mutations in the protoporphyrinogen oxidase gene. Homozygous variegate porphyria results from mutations in both alleles of the protoporphyrinogen oxidase (PPOX) gene. Our patient, a 36-year-old woman, has severe cutaneous manifestations. Her clinical and biochemical features are similar to the few other reported cases, including onset before 18 months of age, photosensitivity, absence of acute porphyric attacks, and elevated erythrocyte protoporphyrin. mutation analysis of the PPOX gene revealed an in-frame 12 bp insert (c. 657-658 ins AAGGCCAGCGCC) encoding lysine-alanine-serine-alanine (KASA), and a G to A transition at the splice donor site of exon 11 (IVS 11-1 G-->A). Neither of these mutations has been reported previously. Our patient's mother has the splice site mutation and has had acute porphyric episodes. A maternal first cousin has the same mutation but no clinical manifestations. The medical and family history of our patient's father is uncertain. ( info) |
6/37. Identification of the first variegate porphyria mutation in an indigenous black South African and further evidence for heterogeneity in variegate porphyria. Variegate porphyria is an autosomal dominant disorder of haem metabolism resulting from reduced levels of the penultimate enzyme in the pathway, protoporphyrinogen oxidase. Here we investigate the molecular basis of variegate porphyria in four non-R59W South African families. We report the identification of the first mutation in the protoporphyrinogen oxidase gene in a black South African individual (V290M). In addition, we document three further mutations, a missense mutation (L15F), a deletion followed by a substitution [c769delG;770T > A], and a nonsense mutation (Q375X), in individuals of European or mixed ancestry. Our data provide further evidence of genetic heterogeneity in south africa. ( info) |
7/37. Oxcarbazepine in focal epilepsy and hepatic porphyria: a case report. PURPOSE: Despite the development of new antiepileptic agents (AEDs), the therapy of epilepsies along with hepatic porphyrias remains difficult. Most AEDs such as carbamazepine (CBZ), phenytoin (PHT), valproate (VPA), and lamotrigine (LTG) may precipitate clinically latent porphyria by inducing hepatic metabolism and increasing hepatic heme synthesis. Actually, only gabapentin (GBP), an AED without any hepatic metabolism, is known as a potential therapy for partial seizures in patients having hepatic forms of porphyria. methods: We present the case of a 28-year-old man with porphyria cutanea tarda (PCT) who has had pharmacoresistant epilepsy with complex partial and secondarily generalized seizures since early childhood. Despite having undergone several AED therapies over the years, no seizure-free interval had been observed. Only CBZ could cause a seizure reduction, but this treatment had to be discontinued as an elevation of the transaminases as well as pruritus and erythema were noted. The patient was then started on oxcarbazepine (OCBZ), a ketoanalogue of CBZ similar in its pharmacologic mechanism as well as its clinical use, but which, in contrast to CBZ, has only a low hepatic induction of microsomal enzymes. A final maintenance dose four times higher than that of CBZ was prescribed. RESULTS: In the follow-up, the patient stopped having seizures, and his liver functions became normal. CONCLUSIONS: It can be concluded that OCBZ can successfully be administered to patients with hepatic porphyria and focal epilepsy who did not respond to treatment with GBP. ( info) |
8/37. Non-alcoholic steatohepatitis induced by carbamazepine and variegate porphyria. A 42-year-old woman presented with acute bullous skin lesions and angio-oedema that had developed 3 months after initiation of treatment with carbamazepine for epilepsy. Chromatographic analysis of urinary porphyrins was compatible with variegate porphyria. This was manifested initially by neurological symptoms that were mistaken for epilepsy and later by cutaneous symptoms also. Histological findings excluded hepatic porphyria, but revealed severe fatty changes thought to be caused by idiosyncratic metabolism of carbamazepine. While the porphyrinogenicity of carbamazepine is well known, the presence of variegate porphyria has not been reported. The toxic hepatic effects of the drug on hepatic cytochrome P-450, which is involved in haem metabolism, could have aggravated the pre-existent porphyria, provoking the onset of skin lesions. ( info) |
9/37. Neonatal-onset hereditary coproporphyria with male pseudohermaphrodism. The appearance of hereditary coproporphyria (HCP) before puberty is very rare, and all reported cases of early-onset HCP have been in the homozygous or the compound heterozygous state. Some have been identified as harderoporphyria, which is a rare erythropoietic variant form of HCP. These conditions can be differentiated by molecular analysis because the gene abnormality responsible for harderoporphyria seems to be unique (K404E). Early-onset HCP, not harderoporphyria, is reported with a gene mutation in the heterozygous state and male pseudohermaphrodism. It was shown that adrenal gland hypofunction resulted in male pseudohermaphrodism. This case demonstrates the possibility that abnormalities of steroid metabolism influence porphyria. ( info) |
10/37. Variegate porphyria with coexistent decrease in porphobilinogen deaminase activity. Variegate porphyria is a rare disease caused by a deficiency of protoporphyrinogen oxidase. In most cases, the clinical findings are a combination of systemic symptoms similar to those occurring in acute intermittent porphyria and cutaneous lesions indistinguishable from those of porphyria cutanea tarda. We report on a 24-year-old woman with variegate porphyria who, after intake of lynestrenol, developed typical cutaneous lesions but no viscero-neurological symptoms. The diagnosis was based on the characteristic urinary coproporphyrin and faecal protoporphyrin excretion patterns, and the specific peak of plasma fluorescence at 626 nm in spectrofluorometry. Biochemical analysis revealed that most of the family members, though free of clinical symptoms, excrete porphyrin metabolites in urine and stool similar to variegate porphyria, accompanied by a significant decrease of porphobilinogen deaminase activity of a range which is ordinarily found in patients with acute intermittent porphyria only (approximately 50%). These data first led to the assumption of two separate and independently inherited genetic defects, similar to the dual porphyria of Chester. Molecular analysis, however, revealed only a missense mutation of the protoporphyrinogen oxidase gene, but not of the porphobilinogen deaminase gene. Thus, in the family presented, porphobilinogen deaminase deficiency is likely to be a phenomenon secondary to the genetic defect of protoporphyrinogen oxidase. ( info) |