J. Lamoril

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 probands 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.

The V249I polymorphism of the CX3CR1 gene is associated with fibrostenotic disease behavior in patients with Crohn's disease.

Objectives CX3CR1, the receptor of CX3CL1/fractalkine, is involved in regulation of inflammatory response and the CX3CR1-I249-M280 naturally occurring mutants are associated with altered binding to the ligand. Our aim was to evaluate the frequency of CX3CR1 V249I and T280M polymorphisms and NOD2/CARD15 mutations in Crohns disease patients and to search for a relationship with phenotype. Methods Clinical data were retrospectively collected. V249I and T280M polymorphisms of CX3CR1 gene and NOD2/CARD15 mutations (R702W, G908R, 3020InsC) were identified. Results Two hundred and thirty-nine patients (140 females, 39.7±14.1 years) were included. About 37.4% were heterozygous and 8.8% were homozygous for the V249I CX3CR1 polymorphism, 18.1% were heterozygous and 1.3% homozygous for the T280M CX3CR1 polymorphism and 35.9% had at least one of the three mutations of NOD2/CARD15. The T280M CX3CR1 polymorphism was not associated with any phenotype. In univariate analysis, stenosis was significantly associated with both V249I CX3CR1 polymorphism and 3020InsC NOD2/CARD15 mutations. In smoker patients carrying the CX3CR1 allele I249, there was a significant increase in the frequency of fibrostenosing disease [P=0.005, odds ratio (OR): 3.25] whereas this relationship disappeared in the group of nonsmokers (P=0.72). In multivariate analysis, 3020InsC NOD2/CARD15 mutations and the V249I CX3CR1 polymorphism were independent risk factors for intestinal stenosis (P=0.046, OR: 1.8 and P=0.044, OR: 2.4, respectively). Conclusion In Crohns disease, V249I CX3CR1 polymorphism is associated with intestinal strictures, particularly in smokers. This association is independent of CARD15 mutations.

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‐&agr; 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.

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 basd 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.

[Direct to consumer genetic testing: is it the moment?].

Since the development of new human genome sequencing technologies at the beginning of the 2000, commercial companies have developped direct to consumer genomic services, which means without medical prescription. From 2007 to 2013, many companies have offered services assesing associated risk with human public health in the world especially in the United States. This kind of company is forbidden in France. From 2009 to 2013, in United States, under the pressure of national or state health administrations, these companies have been progressively forbidden. However, in certain parts of the world, companies are still offering such services. The latter raise many different questions such as ethical, juridical, medical, scientific, educative, professional one. Many studies and debates have demonstrated their limit and the lack of usefulness and advantage in the field of human health for the time being. The commercialization of this type of services has arrived all too soon et is not yet ripe. In our time of globalization, with the lack of international rules controlling direct access to genetic services in the field of human health, there is an urgent need to regulate. International administrations and politicians must act fast. Inevitably, under the pressure of lobbies and citizens, companies (multinational or not) will develop especially as 1) new sequencing technologies evolve rapidly, 2) are cheaper from year to year, 3) scientific and medical knowledges are progressing quickly, 4) services are spreading faster through the web and other networks.

La médecine génomique, une réalité en pleine évolutionDeuxième partie

New sequencing techniques are revolutionizing medical practice as its applications are numerous and considerable. We are living a technological turning point in molecular medicine. Indeed, thanks to these new machines, this technological leap allowed us to analyse the human genome with an elarged or even a total view. Genome analysis has applications in all medical fields from now on. Gene analysis in parallel with personalized therapy help in prolonged survival or even cures in some cancers or other diseases. Genetics is progressively arriving in every field of clinical practice. A new way of thinking clinics is born. This publication describes in its main lines these new applications, their problems and their challenges for geneticists as much as for other practitioners in the medical fields.

Trechniques d’amplification génique autres que la PCR

RésuméLa PCR constitue la méthode d’amplification génique la plus utilisée dans le monde de la biologie moléculaire tant dans le domaine de la recherche que de celui de la biologie clinique.Des techniques alternatives à la PCR ont été décrites et certaines d’entre elles sont commercialisées sous forme de kit.