GEMHEP multicenter quality control study of PCR detection of GB virus C/hepatitis G virus RNA in serum.

PCR is, to date, the only available tool for the detection of GB virus C (GBV-C) and hepatitis G virus (HGV) RNAs. Twenty-two French laboratories participated in a quality control study to assess the sensitivity and specificity of their procedures. The panel included 13 positive controls and 7 negative controls. The laboratories used either in-house PCR techniques adapted from the literature or partly standardized commercial tests. Three laboratories performed faultlessly with the entire panel. Most laboratories had excellent specificity (100% in 20 of 22 laboratories). Sensitivity was acceptable (85 to 100%) in 15 centers and insufficient (38 to 77%) in 7. As with nonstandardized in-house PCR, the commercial assays gave discrepant performances in different laboratories. These results suggest that laboratories willing to use PCR for detection of GBV-C/HGV RNA for research or diagnostic purposes should participate in multicenter quality control trials.     

Neurological, dermatological and biological manifestations of porphyria variegata. A study of 3 families of Italian origin in Marseilles area]

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)     

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.     

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.      

Mutations in human CPO gene predict clinical expression of either hepatic hereditary coproporphyria or erythropoietic harderoporphyria

Hereditary coproporphyria (HCP), an autosomal dominant acute hepatic porphyria, results from mutations in the gene that encodes coproporphyrinogen III oxidase (CPO). HCP (heterozygous or rarely homozygous) patients present with an acute neurovisceral crisis, sometimes associated with skin lesions. Four patients (two families) have been reported with a clinically distinct variant form of HCP. In such patients, the presence of a specific mutation (K404E) on both alleles or associated with a null allele, produces a unifying syndrome in which hematological disorders predominate: 'harderoporphyria'. Here, we report the fifth case (from a third family) with harderoporphyria. In addition, we show that harderoporphyric patients exhibit iron overload secondary to dyserythropoiesis. To investigate the molecular basis of this peculiar phenotype, we first studied the secondary structure of the human CPO by a predictive method, the hydrophobic cluster analysis (HCA) which allowed us to focus on a region of the enzyme. We then expressed mutant enzymes for each amino acid of the region of interest, as well as all missense mutations reported so far in HCP patients and evaluated the amount of harderoporphyrin in each mutant. Our results strongly suggest that only a few missense mutations, restricted to five amino acids encoded by exon 6, may accumulate significant amounts of harderoporphyrin: D400-K404. Moreover, all other type of mutations or missense mutations mapped elsewhere throughout the CPO gene, lead to coproporphyrin accumulation and subsequently typical HCP. Our findings, reinforced by recent crystallographic results of yeast CPO, shed new light on the genetic predisposition to HCP. It represents a first monogenic metabolic disorder where clinical expression of overt disease is dependent upon the location and type of mutation, resulting either in acute hepatic or in erythropoietic porphyria.     

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.     

Combined factor V leiden (G1691A) and prothrombin (G20210A) genotyping by multiplex real-time polymerase chain reaction using fluorescent resonance energy transfer hybridization probes on the Rotor-Gene 2000.

Several methods have been developed to detect common single point mutations in the factor V and prothrobin genes that are risk factors for thrombophilia. Most are based on PCR followed by restriction enzyme digestion and electrophoresis (RFLP), but gel analysis has certain limitations, and alternative detection methods, including real-time PCR, have therefore been developed. In this study we developed and evaluated a combined factor V Leiden and prothrombin (G20210A) genotyping method based on multiplex real-time PCR with fluorescent resonance energy transfer (FRET) hybridization probes on the Rotor-Gene 2000. Two hundred subjects were screened for the two mutations. The FRET assay clearly discriminated among wild-type, homozygous and heterozygous status for the two mutations, and the results were in full agreement with those of the RFLP assay. This robust FRET probe-based assay also has a higher throughput capacity than conventional methods, handling up to 72 samples in 90 min.