Search

We report the fifth French case of fatal familial insomnia, characterized by a mutation at codon 178 of prion protein gene and by heterozygoty (Met/Val) at codon 129. The clinical picture included cerebellar ataxia, dysautonomia and frontal lobe syndrome. Prion protein gene analysis was performed in order to support a diagnosis of Creutzfeldt-Jakob disease and assert the diagnosis of fatal familial insomnia. Neuropathologic analysis showed unusual changes including severe neuronal loss in the inferior olive and the dentate nucleus, and absence of obvious lesions in the thalamus. Moreover, spongiform changes were moderate in the superior temporal cortex and the occipital cortex. There was no spongiform change in frontal cortex. Abnormal prion protein (PrP(res)) was mainly evidenced in the parietal cortex. Molecular genetic study of the PRNP gene should be performed in patients who present with a cerebellar ataxia of equivocal origin.

We studied the diagnostic value of detecting protein 14-3-3 and of assaying neuronal specific enolase (NSE) in the cerebrospinal fluid of 150 patients with suspected sporadic Creutzfeldt-Jakob disease registered in an epidemiology research program between 1991 and 1996. Sensitivity and specificity of these two tests were high. This study confirms results reported earlier and authorizes a new definition of Creutzfeldt-Jakob disease which gives protein 14-3-3 the same diagnostic value as EEG recordings for classifying sporadic cases.

Recent developments in animal and humans transmissible spongiform encephalopathies have motivated a study on incidence and risk factors of Creutzfeldt-Jakob disease (CJD) in France and 4 other European countries.CJD cases were ascertained through a national network including 250 neurological departments or neuropathological laboratories. CJD cases were classified as definite, probable or possible. Overall incidence rate and age-standardized incidence rates by department were computed. Standardized incidence ratios and their 95% confidence intervals were computed for comparing observed and expected number of CJD cases in each department.Between 1992 and 1995, 216 CJD cases were registered (mean incidence rate: 0.87 per million inhabitants). The distribution of CJD cases was heterogeneous (p0.007). Nevertheless, the distribution of standardized incidence ratios fitted quite well a Poisson distribution. The observed number of CJD cases was significantly higher than expected in 4 departments and lower in 1 department.Incidence of CJD in France is similar to that observed in other European countries. Analysis of distribution of CJD cases by department showed a few significant differences which can be due to random fluctuations.

Scrapie is a transmissible degenerative disease of the central nervous system occurring naturally in sheep. It belongs to the group of prion diseases also affecting man in which an abnormal isoform of the host-encoded prion protein (PrP) accumulating in the brain is responsible for neuronal death. Three main polymorphisms have been described in the sheep PrP gene, at positions 136, 154 and 171. A strong association between susceptibility/resistance to natural scrapie and a dimorphism at codon 136 of the ovine PrP gene has been reported in several breeds, including Romanov. This dimorphism, however, is not found in all scrapie-affected breeds. We have compared the PrP genotypes of Lacaune sheep obtained from enzootically affected flocks with those of apparently healthy sheep. A third variant at codon 171 was also evidenced. The results were compared with those obtained in a single experimental Romanov flock orally challenged with nematode parasites in which scrapie suddenly appeared and killed 80% of the sheep. We present evidence that, even in different epizootological circumstances, the major genetic factor controlling the susceptibility/resistance to natural scrapie in sheep, is represented by codon 171 genotype of the PrP gene. We also suggest that a modification of the allelic effects of codon 136 can occur in heavily infected animals.

Prion diseases, also known as transmissible subacute spongiform encephalopathies (TSSE), are rare neurodegenerative disorders of both humans and animals. Their biochemical hallmark is an accumulation in the brain of an abnormal form of the host-encoded prion protein (PrP). This pathological accumulation could result from a protein conformational change under the influence of unknown factors. The normal function of PrP is unknown. The abnormal form is thought to induce neurodegeneration when experimentally or accidentally introduced in recipient hosts. Such a possibility would explain the transmissible character of these diseases illustrated in humans by iatrogenic contamination. Considerable attention has been focused on the host PrP gene and its relation with the genetic susceptibility of humans and animals. Mutations in PRNP, the gene which encodes PrP in humans, are present in 17% of the patients and might be causative. In patients without any PRNP mutation, a coding polymorphism (129 Met/Val) defines a predisposing factor. Important progress in the molecular genetics of TSSE in both humans and animals have been performed for few years and point out that the development of different forms of these diseases, experimental, iatrogenic or spontaneous, are strongly dependent on the primary structure of the host PrP.

In 1986, a new neurologic disease appeared in the Great Britain's Cattle. According to its histological lesions, this condition belongs to the group of transmissible encephalopathies known as spongiforme encephalopathies (SE). These SE are associated with no-conventional transmission agent (NCTA) or Prion. At the time of writing, over 13,000 cases of Bovine spongiforme encephalopathy (BSE) have occurred in UK. The most likely origin of this dramatic outbreak would be an oral contamination of Cattle by the feeding of sheep carcasses or of all infected with scrapie, another SE, incorporated to concentrates. Possible factors as changes (lower temperatures and reduced use of organic solvents to extract fats) in the rendering process could have preserved the very resistant Prion in these concentrates. The important lessons resulting from our present knowledge and hypothesis are there would be no species barrier to impede transmission of the NCTA through oral route. The question concerns the public health risks posed by BSE. Two related diseases of human are Kuru and Creutzfeldt-Jacob disease. At the present time, based upon epidemiological datas on scrapie, BSE is unlikely to be a major threat to humans. Nevertheless, precautionary steps to reduce a potential risk to an absolute minimum were taken by British regulations and more recently, by European directives.

The main objective of this thesis was to explore the association between genetic variants potentially involved in inter-individual variability of opioids’ response and side effects in the treatment of pain and opiate substitution treatment. Initially, we investigated whether genetic factors influence the response to morphine in the treatment of acute pain. The T allele of the polymorphism ABCB1 c.3435C>T was significantly associated with doses of morphine and the outcome of nausea in a pilot study in Lebanese postoperative patients. Next, we examined the response to morphine in patients with morbid obesity (BMI>40); in these patients, the frequency of the 118G OPRM1 allele and the pain threshold appeared to be higher than in patients with normal BMI. The search for factors influencing the variability in response to methadone in patients treated for drug substitution showed that two polymorphisms (DRD2/ANKK1 TaqIA and OPRM1 c.118A>G) were significantly associated with the maximum doses of methadone. In addition, three factors were associated with the CYP3A phenotype, involved in the metabolism of methadone: the use of benzodiazepines, HIV infection and a polymorphism in POR gene, which encodes an oxidoreductase. Finally, the exploration of the cardiac side effects of methadone has highlighted three factors significantly correlated with QT prolongation: methadone doses, HIV infection and the polymorphism p.Lys897Thr in KCNH2 encoding a cardiac potassium ion channel. This work demonstrates the importance of integrating both clinical and genetic data in the personalized prescription of opioids., L’objectif de cette thèse a été d’explorer l’association entre des variants génétiques impliqués dans la variabilité interindividuelle de la réponse au traitement par les opioïdes et la survenue d’effets secondaires. Nous avons recherché si des facteurs génétiques influençaient la réponse à la morphine dans le traitement de la douleur aigüe. L’allèle T du polymorphisme c.3435C>T d’ABCB1 est significativement associé aux doses de morphine et à la survenue de nausées dans une étude pilote chez des patients libanais en post-opératoire. Ensuite, l’étude de la réponse à la morphine chez des patients présentant une obésité morbide a montré que la fréquence de l’allèle 118G d’OPRM1 et le seuil de sensibilité à la douleur sont plus élevés que chez les patients à poids normal. La recherche des facteurs influençant la variabilité de la réponse à la méthadone chez des patients toxicomanes traités pour substitution a mis en évidence deux polymorphismes (TaqIA de DRD2/ANKK1 et c.118A>G d’OPRM1) significativement associés à la dose maximale de méthadone administrée. Trois facteurs sont associés au phénotype CYP3A, impliqué dans le métabolisme de la méthadone: la prise de benzodiazépines, l’infection par le VIH et un polymorphisme de POR, gène qui code une oxydoréductase. De plus, le travail mené sur les effets secondaires cardiaques de la méthadone a permis de mettre en évidence trois facteurs corrélés à l’allongement de l’espace QT : la dose, l’infection par le VIH et le polymorphisme p.Lys897Thr de KCNH2 codant pour le canal potassique hERG. Ces travaux contribuent à démontrer l’intérêt d’intégrer des données cliniques et génétiques dans la prescription personnalisée des opioïdes.