Exploration des mécanismes physiopathlogiques à l'origine du syndrome de Rett

PARIS5-BU Méd.Cochin (751142101) / SudocSudocFranceF

Le syndrome de Rett (conséquences transcriptionnelles d'un déficit en MeCP2 ou CDKL5 dans les fibroblastes humains)

PARIS-BIUP (751062107) / SudocSudocFranceF

Allo-immunisation foeto-maternelle Rhésus D (stratégie diagnostique, traitement prophylactique et prévention ciblée)

PARIS-BIUP (751062107) / SudocSudocFranceF

MeCP2 is involved in random mono-allelic expression for a subset of human autosomal genes

International audienceWidespread random monoallelic gene expression (RMAE) effects influence about 10% of human genes. However, the mechanisms by which RME of autosomal genes is established and those by which it is maintained both remain open questions. Because the choice of allelic expression is randomly performed cell-by-cell, the RMAE mechanism is not observable in non-clonal cell populations or in whole tissues. Several target genes of MeCP2, the gene involved in Rett syndrome (RTT), have been previously described as subject to RMAE, suggesting that MeCP2 may be involved in the establishment and/or maintenance of RME of autosomal genes. To improve our knowledge on this largely unknown phenomenon, and to study the role of MeCP2 in RMAE, we compared RMA gene expression profiles in clonal cell cultures expressing wild-type MeCP2 versus mutant MeCP2 from a RTT patient carrying a pathogenic non-sense variant. Our data clearly demonstrated that MeCP2 deficiency does not affect significantly allelic gene expression of X-linked genes, imprinted genes as well as the RMAE profile in the majority of genes. However, the functional deficiency in MeCP2 appeared to disrupt the mono-allelic or the bi-allelic expression of at least 49 genes allowing us to define a specific signature of MECP2 mutated clones

Vers une généralisation du diagnostic prénatal non-invasif des maladies monogéniques ? État des lieux et perspectives

Objectives: The screening of fetal aneuploidies and non-invasive prenatal diagnosis of monogenic diseases (NIPD-MD) both rely on the study of free fetal DNA in maternal circulation, but their respective rise was unequal. Development of NIPD-MD has taken longer as it represents a less attractive commercial dynamic for industry, but also because it usually involves the development of tailored tests specific to each pathogenic variant.Methods: We have carried out a review of the literature on the various indications and technologies involved in the use of NIPD-MM. We present its current implementation and its development in France.Results: To date, NIPD-MD has been routinely offered in France for several years by the laboratories of the French NIPD-MD network but remains mostly limited to the exclusion of paternal or de novo variants, the exclusion DPNI-MD. Indeed, it is still difficult to study the transmission of maternal variants from circulating free DNA analysis, due to its biological complexity: coexistence and predominance of similar DNA sequences of maternal origin. Different strategies, either direct or indirect, are being evaluated to establish fetal status regardless of the parental origin of the disease or its transmission mode. The emergence of commercial screening solutions for monogenic diseases complements the arsenal of prenatal exploration tools for these diseases.Conclusion: The multitude of existing technologies and protocols may complicate the information provided during antenatal consultations, but mastery of know-how and knowledge of ethical issues of NIPD-MD will ensure optimal service and better management of pregnancies at risk of transmitting monogenic disease

Cold Case: Patient with only one CAPN3 variant

International audienc

DMD and West syndrome.

Duchenne Muscular Dystrophy (DMD) is the most frequent muscular dystrophy in childhood, with a worldwide incidence of one in 5000 live male births. It is due to mutations in the dystrophin gene leading to absence of full-length dystrophin protein. Central nervous system involvement is well-known in Duchenne Muscular Dystrophy. The multiple dystrophin isoforms expressed in brain have important roles in cerebral development and functioning. The association of Duchenne Muscular Dystrophy with seizures has been reported, and there is a higher prevalence of epilepsy in Duchenne Muscular Dystrophy patients (between 6.3% and 12.3%) than in the general pediatric population (0.5-1%). Duchenne Muscular Dystrophy patients may present with focal seizures, generalized tonic-clonic seizures or absences. We report on two boys in whom Duchenne Muscular Dystrophy is associated with epileptic spasms and hypsarrhythmia that fulfil the criteria for West syndrome, thus extending the spectrum of seizure types described in Duchenne Muscular Dystrophy patients

Association Between Plasma Rituximab Concentration and the Risk of Major Relapse in Antineutrophil Cytoplasmic Antibody–Associated Vasculitides During Rituximab Maintenance Therapy

International audienceObjective Interindividual variability in response to rituximab remains unexplored in antineutrophil cytoplasmic antibody (ANCA)–associated vasculitides. Rituximab pharmacokinetics (PK) and pharmacodynamics (PD) as well as genetic polymorphisms could contribute to variability. This ancillary study of the MAINRITSAN 2 trial aimed to explore the relationship between rituximab plasma concentration, genetic polymorphisms in PK/PD candidate genes, and clinical outcomes. Methods Patients included in the MAINRITSAN2 trial ( ClinicalTrials.gov identifier: NCT01731561) were randomized to receive a 500‐mg fixed‐schedule rituximab infusion or an individually tailored regimen. Rituximab plasma concentrations at month 3 (CM3) were assessed. DNA samples (n = 53) were genotyped for single‐nucleotide polymorphisms within 88 putative PK/PD candidate genes. The relationship between PK/PD outcomes and genetic variants was investigated using logistic linear regression in additive and recessive genetic models. Results One hundred and thirty‐five patients were included. The frequency of underexposed patients (<4 μg/ml) in the fixed‐schedule group was statistically lower compared to that in the tailored‐infusion group (2.0% versus 18.0%; P = 0.02, respectively). Low rituximab plasma concentration at 3 months (CM3 <4 μg/ml) was an independent risk factor for major relapse (odds ratio 6.56 [95% confidence interval (95% CI) 1.26–34.09]; P = 0.025) at month 28 (M28). A sensitivity survival analysis also identified CM3 <4 μg/ml as an independent risk factor for major relapse (hazard ratio [HR] 4.81 [95% CI 1.56–14.82]; P = 0.006) and relapse (HR 2.70 [95% CI 1.02–7.15]; P = 0.046). STAT4 rs2278940 and PRKCA rs8076312 were significantly associated with CM3 but not with major relapse onset at M28. Conclusion These results suggest that drug monitoring could be useful to individualize the schedule of rituximab administration within the maintenance phase