Comprehensive cytochrome P450 CYP1A2 gene analysis in French caucasian patients with familial and sporadic porphyria cutanea tarda.

BACKGROUND: Porphyria cutanea tarda (PCT), the most frequent type of porphyria, results from decreased uroporphyrinogen decarboxylase (UROD) activity. Two forms of PCT have been described: a familial form (fPCT) characterized by the inherited decrease of UROD activity in all tissues and a sporadic form (sPCT) characterized by decreased UROD activity in the liver. Cytochrome P450 CYP1A2 plays a major role in triggering experimental uroporphyria in rodents. It has been suggested that the highly inducible -163A/A genotype of the CYP1A2 gene could confer a heightened risk of PCT in patients. OBJECTIVES: To examine the impact of CYP1A2 polymorphisms on the clinical course of PCT. METHODS: We performed an extensive CYP1A2 gene analysis in 96 (48 fPCT and 48 sPCT) unrelated French caucasian patients with PCT and in 99 healthy volunteers of similar ethnic origin. Results We did not observe any difference in CYP1A2 allele distribution, including a novel and rare CYP1A2 c.1063C>T (p.R355W) single nucleotide polymorphism. In addition, we compared the frequency of the -163A highly inducible allele both in patients with symptomatic fPCT (n = 48) and in asymptomatic UROD gene mutations carrier relatives (n=54). This variant was not over-represented in patients with PCT vs. either healthy volunteers or asymptomatic UROD gene mutation carriers. CONCLUSIONS: The CYP1A2 genotype does not appear to be a major susceptibility factor in the development of fPCT or sPCT in the French population.

Cutaneous aseptic neutrophilic abscesses and Yersinia enterocolitica infection in a case subsequently diagnosed as Crohn's disease.

We report the case of a man who presented cutaneous aseptic abscesses, a rare form of neutrophilic disease, associated with Yersinia enterocolitica infection and who was later diagnosed as having Crohn's disease (CD). Genetic analysis showed that the patient had a mutation in the caspase activation recruitment domain 15/nucleotide oligomerization domain 2 gene (R702W heterozygote). This case is in keeping with recent evidence in the literature which suggests that CD is a disease linked to abnormal immune responses to enteric bacteria in genetically susceptible individuals. Further understanding of the innate immune system should provide new insights into the pathogenesis of these inflammatory diseases.

Detection by PCR of Toxoplasma gondii in blood in the diagnosis of cerebral toxoplasmosis in patients with AIDS.

The polymerase chain reaction (PCR) for amplification of Toxoplasma gondii DNA was performed prospectively in the blood of 19 patients with AIDS and cerebral toxoplasmosis. The B1 gene and TGR1E sequence were used as targets and results were confirmed by hybridisation. Controls consisted of 24 HIV infected patients with tissue culture proven T gondii parasitaemia and 57 HIV infected patients without toxoplasmosis. PCR was positive with both targets in 20 of 24 samples (84%) from patients with parasitaemia. Three of 57 samples (5%) from patients without toxoplasmosis were PCR positive with either target, but none was positive with both targets. Only three of the 19 patients (16%) with cerebral toxoplasmosis had a positive PCR with both targets before the start of specific treatment. PCR performed in blood is of little diagnostic value in cases of cerebral toxoplasmosis but could be useful in patients with disseminated infection.

Evaluation of mutation screening by heteroduplex analysis in acute intermittent porphyria: comparison with denaturing gradient gel electrophoresis.

Acute intermittent porphyria is the major autosomal dominant form of acute hepatic porphyrias. The disease is due to mutations in the gene encoding for porphobilinogen deaminase (PBGD). Many different strategies have been developed to screen for mutations. However the high prevalence (0.6 per thousand) of PBGD gene defect, the large allelic heterogeneity of mutations (n = 130), and the limitations of the PBGD enzymatic assay for asymptomatic patients' detection, require for diagnosis an efficient and easy to handle strategy for locating mutations within the PBGD gene. In a recent study the sensitivity of the denaturing gradient gel electrophoresis (DGGE) technique was 100%. However DGGE requires the preparation of gradient gels and the use of primers with long GC-clamps; thus alternative methods should be preferable in the clinical laboratory. We have compared the detection rate of DGGE with heteroduplex analysis (HA) using 16 characterized PBGD gene mutations. Six different HA conditions were used to determine the efficiency of the method, including: (1) MDE (mutation detection enhancement) gel concentration; (2) addition of urea and sodium dodecyl sulfate (SDS); (3) radioactive labelling. The sensitivity of each HA condition varied from 31 to 81% vs. 100% in DGGE analysis. HA using 1 x MDE with 15% urea with or without 0.55% SDS was the most sensitive condition. This first comparative study of DGGE and HA mutation screening methods suggests that DGGE is a more sensitive screening assay than optimized HA. However, because of its simplicity HA should be considered as an efficient alternative mutation screening method.

Amantadine for chronic hepatitis C: pilot study in 14 patients.

BACKGROUND: Amantadine, a widely available antiviral drug, has been previously reported to be effective in patients with chronic hepatitis C who failed to respond to interferon-alpha therapy. Nevertheless, its efficacy has not been fully studied, particularly in naive patients. OBJECTIVE AND DESIGN: We conducted a pilot study to determine the efficacy and the safety of amantadine as initial therapy in patients with chronic hepatitis C. METHODS AND PARTICIPANTS: Fourteen consecutive patients (mean age, 40 years; M/F ratio, 9/5) with chronic hepatitis C, elevated alanine aminotransferase (ALT) and without cirrhosis were treated with a 6-month course of amantadine, 100 mg orally twice daily. Main outcome measures were ALT concentrations and serum hepatitis C virus-RNA (HCV-RNA) levels at the end of therapy. RESULTS: All adverse events were mild or moderate and were not treatment limiting. At the end of treatment, all patients had detectable serum HCV-RNA and only one patient had a normal ALT level. The serum HCV-RNA median level and the ALT median level were not significantly different at the end of treatment as compared to baseline levels. CONCLUSIONS: Our results show that amantadine alone cannot be recommended as an alternative therapy in patients with chronic hepatitis C.

Thyroid hormone extraction by plasma exchange: a study of extraction rate.

How to obtain an optimal efficiency of plasma exchanges in the treatment of severe hyperthyroidism has not been defined. In order to evaluate how long the exchanges must be continued to be fully effective in extracting thyroid hormones, we evaluated the extraction rate by repeated plasma sampling in two hyperthyroid patients and three euthyroid subjects who underwent a total of seven exchanges. Plasma concentrations of thyroid hormones were also determined just before, just after, and 24 hours following the exchange. The hormonal removal rate did not fall dramatically during the exchange, so that its efficiency--in terms of hormone extraction--depends closely on its duration. The determination of plasma thyroid hormone concentrations after the exchange does not appear to be useful in evaluating the thyroid hormone loss since these concentrations may not change in spite of the hormonal extraction.

[Neurological, dermatological and biological manifestations of porphyria variegata. A study of 3 families of Italian origin in Marseilles area]. / Manifestations neurologiques, dermatologiques et biologiques de la porphyrie variegata, Etude de trois familles d'origine italienne vivant dans la région marseillaise.

Three kindreds of Italian descent with variegate porphyria are described. These families are now living in Marseilles and surrounding regions. The first kindred originating from Torre del Greco, near Naples, is living in Arles. This family includes two propositi who experienced an acute attack with visceral and neuropsychiatric manifestations. The family's survey was carried out by measuring protoporphyrogen oxidase (PO) activity in lymphocytes (normal values = 4.8 +/- 1.2). Seven of the 20 subjects tested, beside the two propositi, were found to be asymptomatic carriers (PO < 3.6). The first index patient, a 41-year old man, was first observed at the age of 31 with acute and psychiatric manifestations after rifampicin treatment; the cutaneous symptoms appeared one year later. For the second propositus, a woman presenting with abdominal and psychiatric manifestations, the age of onset was 38 years; the acute attack had no recognizable cause; she had mild skin lesions and initially was incorrectly diagnosed as intermittent acute porphyria; the diagnosis of variegate porphyria was only established at the age of 50 years. The second family, originating from la Spezia and Vernazza, is living in Marseilles. The propositus, a 50-year old man, developed cutaneous symptoms at the age of 30. A diagnosis of porphyria cutanea tarda was initially made. The first and unique acute attack with abdominal and neurological manifestations recurred at the age of 41. The diagnosis of variegate porphyria was established on laboratory data. Physical stress was probably the cause of the acute attack. Beside the propositus, out of 9 subjects tested 6 were asymptomatic carriers.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of Toxoplasma gondii parasitemia by polymerase chain reaction in perorally infected mice.

Sequential blood samples collected from mice infected perorally with an avirulent strain of T. gondii were analysed for parasite DNA by a polymerase chain reaction method (PCR). Two pairs of primers specific for gene B1 and the repetitive DNA sequence TGR1E were used for DNA amplification. Amplified products were detected by means of electrophoresis with ethidium bromide staining. Parasitemia was also determined by cell culture. Parasitemia was never detected by the tissue culture method, whereas parasite DNA was continuously detected with PCR from day 2 to day 21. These results confirm the high sensitivity of PCR for T. gondii DNA in blood, and show that circulating DNA is present for long periods in mice following primary infection.

Molecular abnormalities of coproporphyrinogen oxidase in patients with hereditary coproporphyria.

Genetic defects of coproporphyrinogen oxidase (CPO) lead to hereditary coproporphyria, an inherited autosomal dominant porphyria. The recent cloning of human cDNAs and of the gene encoding CPO permits deducing the primary structure of the CPO protein and elucidating the molecular basis of HC in some families.

A molecular defect in coproporphyrinogen oxidase gene causing harderoporphyria, a variant form of hereditary coproporphyria.

Hereditary coproporphyria (HC) is an acute hepatic porphyria with autosomal dominant inheritance caused by a deficient activity of coproporphyrinogen IX oxidase (CPX). We previously described harderoporphyria, a homozygous variant form of coproporphyria in three siblings, characterized by a massive excretion of harderoporphyrin and a marked decrease of coproporphyrinogen IX oxidase activity. In this kindred, the transmission of the disease was autosomal recessive. In the present study, sequencing of cDNA and genomic DNA from these patients revealed a point mutation resulting in a lysine to glutamic acid substitution (K304E) in exon 6 of the gene and the absence of the normal allele, suggesting a homozygous state for the mutation. Expression studies of normal and mutated cDNAs in E. coli demonstrated that this amino acid substitution was responsible for the important decrease in the enzyme activity and for the accumulation of harderoporphyrin. The Michaelis constant of the mutated enzyme was 10-fold higher than normal suggesting that the lysine at position 304 is important for binding the substrate: a slightly increased sensitivity to thermal denaturation was also observed.

Molecular analysis of porphobilinogen (PBG) deaminase gene mutations in acute intermittent porphyria: first study in patients of Slavic origin.

Acute intermittent porphyria (AIP) is an autosomally dominant inherited metabolic disorders caused by decreased activity of porphobilinogen deaminase, the third enzyme in the human heme biosynthetic pathway. We report here the first mutations in the human porphobilinogen deaminase gene in seven unrelated patients from the Czech and Slovak Republics with acute intermittent porphyria. We used denaturing gradient gel electrophoresis to screen all 15 exons and exon/intron boundaries of the porphobilinogen deaminase gene. Polymerase chain reaction products of abnormal migration patterns were subjected to direct sequencing to identify the causative mutations. Thus we revealed four novel mutations and three which have been previously described. Of the four novel mutations, two were mis-sense (G24S, V267M), one was a single base insertion (158insA) that produced a stop codon 12 codons downstream, and one was a single base substitution in intron 12 (771 + 1) resulting in a splicing defect. The three previously detected mutations were mis-sense mutations (R26C, R26H, G111R). These results suggest a high allelic heterogeneity in Czech and Slovak patients.

Detection of four novel mutations in the porphobilinogen deaminase gene in French Caucasian patients with acute intermittent porphyria.

Acute intermittent porphyria (AIP) is an autosomal dominant disorder characterized by alterations of the gene encoding porphobilinogen deaminase (PBGD: EC 4.3.1.8), the third enzyme of the heme biosynthetic pathway. The molecular heterogeneity of the mutations causing AlP has been demonstrated with a reported predominance of single base substitutions resulting in amino acid changes. The molecular basis of AIP in four French patients was investigated using denaturing gradient gel electrophoresis followed by direct sequencing. We describe four different novel mutations that affected exon 12 (a frameshift and an exon skipping), exon 4 (a stop codon) and exon 15 (a frameshift inducing a stop codon). This study further documents the molecular heterogeneity of mutations in the PBGD gene in the French Caucasian population and reports types of mutations relatively uncommon in AIP.

Review: molecular pathogenesis of hepatic acute porphyrias.

The molecular cloning of cDNA and genes encoding enzymes of the haem biosynthetic pathway have permitted the genetic defects underlying acute intermittent porphyria (AIP) and hereditary coproporphyria to be unravelled. In AIP, many different gene abnormalities have been documented since 1989. The prevalence of specific defective alleles among AIP families depends on which human population is studied. Founder effects are likely to account for a high frequency of a single mutation in Finland and, to a lesser extent, in Holland, while many other mutations have only been found once, each of them in a single family. In hereditary coproporphyria several different mutations have already been identified since 1994, suggesting that a large allelic heterogeneity also exists. The search for mutations in variegate porphyria has just started since the recent publication of the human cDNA sequence. Direct detection of the mutations using DNA analysis brings a growing contribution to the detection of asymptomatic carriers among relatives of porphyric patients and will, therefore, improve the prevention of acute attacks.

Human erythropoietic protoporphyria: two point mutations in the ferrochelatase gene.

The molecular basis of the ferrochelatase defect responsible for human Erythropoietic Protoporphyria (EPP), a usually autosomal dominant disease, was investigated in a family with an apparently homozygous patient. Two mutations of the ferrochelatase gene were identified by sequencing the proband's cDNA after in vitro amplification of the mRNA and subcloning of the amplified products. One mutation results from a G to T transition at nucleotide 163 which produces a glycine to cysteine substitution at amino-acid residue 55 (G-55-C). The other one was a G to A change at nucleotide 801, leading to a methionine to isoleucine substitution at amino-acid residue 267 (M-267-I). This EPP patient was then double heterozygous and as expected each of his parents carried one of the mutations. A second similar EPP patient was screened for these mutations with negative results, showing a genetic heterogeneity in EPP.

Acute intermittent porphyria: rapid molecular diagnosis.

Acute intermittent porphyria (AIP) is an autosomal dominant disorder caused by a partial porphobilinogen (PBG) deaminase deficiency. An exon-by-exon denaturing gradient gel electrophoresis (DGGE) analysis followed by direct sequencing of the DNA fragments was performed to investigate molecular defect in 8 unrelated patients living in south of France: one Algerian, two Moroccan and five French patients. We have optimized the DGGE method in order to study at the same time the fifteen exons of the PBG deaminase gene in only one electrophoresis run. Six different mutations were detected by abnormal mobility patterns. After characterization, a C insertion (716 ins C), 2 deletions (589 del 17 bp; 730 del CT), a non-sense mutation (R149X) and 2 missense mutations (A270G; R173W) were found. The R173W missense mutation was found in 3 unrelated patients, and 716 ins C, 589 del 17 bp and A270G were newly described. According to this small AIP samples, sensitivity of the DGGE screening method was 100%.

Mutations in the protoporphyrinogen oxidase gene in patients with variegate porphyria.

Variegate porphyria (VP) is an acute hepatic porphyria with autosomal dominant inheritance due to a partial deficiency of protoporphyrinogen oxidase (PPOX) activity. The molecular defect responsible for VP was investigated by sequencing PPOX gene coding sequence from four patients in three unrelated VP families of French Caucasian origin. In a first patient, a point insertion of a G at position 1022 of the cDNA, produced a frameshift resulting in a premature stop codon. In three other patients from two unrelated families we found a missense point mutation leading to glycine to arginine substitution (G232R) in exon 7. This Gly232 appears to be a strictly conserved residue through evolution. In one VP family, we observed the cosegregation of the G232R missense mutation and the deficient PPOX activity. The mutations reported here are the first to be described in patients with VP and support the conclusion that PPOX gene defects are disease causing mutations in human variegate porphyria.

Inheritance in erythropoietic protoporphyria: a common wild-type ferrochelatase allelic variant with low expression accounts for clinical manifestation.

Erythropoietic protoporphyria (EPP) is a rare autosomal dominant disorder of heme biosynthesis characterized by partial decrease in ferrochelatase (FECH; EC 4.99.1.1) activity with protoporphyrin overproduction and consequent painful skin photosensitivity and rarely liver disease. EPP is normally inherited in an autosomal dominant pattern with low clinical penetrance; the many different mutations that have been identified are restricted to one FECH allele, with the other one being free of any mutations. However, clinical manifestations of dominant EPP cannot be simply a matter of FECH haploinsufficiency, because patients have enzyme levels that are lower than the expected 50%. From RNA analysis in one family with dominant EPP, we recently suggested that clinical expression required coinheritance of a normal FECH allele with low expression and a mutant FECH allele. We now show that (1) coinheritance of a FECH gene defect and a wild-type low-expressed allele is generally involved in the clinical expression of EPP; (2) the low-expressed allelic variant was strongly associated with a partial 5' haplotype [-251G IVS1-23T IVS2microsatA9] that may be ancestral and was present in an estimated 10% of a control group of Caucasian origin; and (3) haplotyping allows the absolute risk of developing the disease to be predicted for those inheriting FECH EPP mutations. EPP may thus be considered as an inherited disorder that does not strictly follow recessive or dominant rules. It may represent a model for phenotype modulation by mild variation in expression of the wild-type allele in autosomal dominant diseases.

Modulation of the phenotype in dominant erythropoietic protoporphyria by a low expression of the normal ferrochelatase allele.

Erythropoietic protoporphyria (EPP) is a monogenic inherited disorder of the heme biosynthetic pathway due to ferrochelatase (FC) deficiency. EPP is generally considered to be transmitted as an autosomal dominant disease with incomplete penetrance, although autosomal recessive inheritance has been documented at the enzymatic and molecular level in some families. In the dominant form of EPP, statistical analysis of FC activities documented a significantly lower mean value in patients than in asymptomatic carriers, suggesting a more complex mode of inheritance. To account for these findings, we tested a multiallelic inheritance model in one EPP family in which the enzymatic data were compatible with this hypothesis. In this EPP family, the specific FC gene mutation was an exon 10 skipping (delta Ex10), resulting from a G deletion within the exon 10 consensus splice donor site. The segregation of all FC alleles within the family was followed using the delta Ex10 mutation and a new intragenic dimorphism (1520 C/T). mRNAs transcribed from each FC allele were then subjected to relative quantification by a primer extension assay and to absolute quantification by a ribonuclease protection assay. The data support the hypothesis that in this family the EPP phenotype results from the coinheritance of a low output normal FC allele and a mutant delta Ex10 allele.

A molecular, enzymatic and clinical study in a family with hereditary coproporphyria.

A 30-year-old woman suffered from acute crises with abdominal, neurological and psychiatric complaints. Urinary haem precursors and faecal porphyrins were excessively elevated compared to the upper level of the normal range. Urinary coproporphyrin isomer III was increased and faecal coproporphyrin isomers I and III showed a complete inversion of the normal ratio. Thus, hereditary coproporphyria was diagnosed in this woman. The father, one brother and a sister were shown to be gene carriers of hereditary coproporphyria by their urinary and faecal excretory constellations. The excretory patterns of the mother and a second brother were normal. Coproporphyrinogen oxidase activity was decreased to 49% and 58%, in the patient and her father, respectively. The mother's enzyme activity was normal (98%). Coproporphyrinogen oxidase concentration was enhanced 1.8-fold and 2.7-fold in the patient and her father, respectively. Mutation analysis revealed the insertion of an adenine at position 857 in exon 4 of the coproporphyrinogen oxidase gene. The gene defect was confirmed by denaturing gradient gel electrophoresis in the patient and her father. The patient was treated by intravenous interval therapy with haem arginate for 10 months, with good clinical and metabolic response.