Christine Coubes

Deep brain stimulation for Huntington's disease: long-term results of a prospective open-label study

UNLABELLED OBJECT.: To date, experience of globus pallidus internus (GPi) deep brain stimulation (DBS) in the treatment of Huntingtons disease (HD) has been limited to a small number of case reports. The aim of this study was to analyze long-term motor outcome of a cohort of HD patients treated with GPi DBS. METHODS Seven patients with pharmacologically resistant chorea and functional impairment were included in a prospective open-label study from 2008 to 2011. The main outcome measure was the motor section of the Unified Huntingtons Disease Rating Scale. The primary end point was reduction of chorea. RESULTS Patients underwent MRI-guided bilateral GPi implantation. The median duration of follow-up was 3 years. A significant reduction of chorea was observed in all patients, with sustained therapeutic effect; the mean improvement on the chorea subscore was 58.34% at the 12-month follow-up visit (p = 0.018) and 59.8% at the 3-year visit (p = 0.040). Bradykinesia and dystonia showed a nonsignificant trend toward progressive worsening related to disease evolution and partly to DBS. The frequency of stimulation was 130 Hz for all patients. DBS-induced bradykinesia was managed by pulse-width reduction or bipolar settings. Levodopa mildly improved bradykinesia in 4 patients. Regular off-stimulation tests confirmed a persistent therapeutic effect of DBS on chorea. CONCLUSIONS GPi DBS may provide sustained chorea improvement in selected HD patients with pharmacologically resistant chorea, with transient benefit in physical aspects of quality of life before progression of behavioral and cognitive disorders. DBS therapy did not improve dystonia or bradykinesia. Further studies including quality of life measures are needed to evaluate the impact of DBS in the long-term outcome of HD.

A new autoinflammatory and autoimmune syndrome associated with NLRP1 mutations: NAIAD (NLRP1-associated autoinflammation with arthritis and dyskeratosis)

Objectives Inflammasomes are multiprotein complexes that sense pathogens and trigger biological mechanisms to control infection. Nucleotide-binding oligomerisation domain-like receptor (NLR) containing a PYRIN domain 1 (NLRP1), NLRP3 and NLRC4 plays a key role in this innate immune system by directly assembling in inflammasomes and regulating inflammation. Mutations in NLRP3 and NLRC4 are linked to hereditary autoinflammatory diseases, whereas polymorphisms in NLRP1 are associated with autoimmune disorders such as vitiligo and rheumatoid arthritis. Whether human NLRP1 mutation is associated with autoinflammation remains to be determined. Methods To search for novel genes involved in systemic juvenile idiopathic arthritis, we performed homozygosity mapping and exome sequencing to identify causative genes. Immunoassays were performed with blood samples from patients. Results We identified a novel disease in three patients from two unrelated families presenting diffuse skin dyskeratosis, autoinflammation, autoimmunity, arthritis and high transitional B-cell level. Molecular screening revealed a non-synonymous homozygous mutation in NLRP1 (c.2176C>T; p.Arg726Trp) in two cousins born of related parents originating from Algeria and a de novo heterozygous mutation (c.3641C>G, p.Pro1214Arg) in a girl of Dutch origin. The three patients showed elevated systemic levels of caspase-1 and interleukin 18, which suggested involvement of NLRP1 inflammasome. Conclusions We demonstrate the responsibility of human NLRP1 in a novel autoinflammatory disorder that we propose to call NAIAD for NLRP1-associated autoinflammation with arthritis and dyskeratosis. This disease could be a novel autoimmuno-inflammatory disease combining autoinflammatory and autoimmune features. Our data, combined with that in the literature, highlight the pleomorphic role of NLRP1 in inflammation and immunity. Trial registration number NCT02067962; Results.

Mutation analysis of the dystrophin gene in Southern French DMD or BMD families : from Southern blot to protein truncation test

TaqI) were defined in a sample of normal, DMD, and BMD Xchromosomes from Southern France. The determination of the grandparental origin of either deletions or point mutations revealed differences depending on the type of the mutation, with most of the deletions occurring in oogenesis and most of the point mutations occurring in spermatogenesis.

Prader‐Willi syndrome: is there a recognizable fetal phenotype?

To determine fetal features, which could lead to the diagnosis of Prader‐Willi syndrome (PWS) during pregnancy.

Comprehensive oligonucleotide array-comparative genomic hybridization analysis: new insights into the molecular pathology of the DMD gene

We report on the effectiveness of a custom-designed oligonucleotide-based comparative genomic hybridization microarray (array-CGH) to interrogate copy number across the entire 2.2-Mb genomic region of the DMD gene and its applicability in diagnosis. The high-resolution array-CGH, we developed, successfully detected a series of 42 previously characterized large rearrangements of various size, localization and type (simple or complex deletions, duplications, triplications) and known intronic CNVs/Indels. Moreover, the technique succeeded in identifying a small duplication of only 191 bp in one patient previously negative for DMD mutation. Accurate intronic breakpoints localization by the technique enabled subsequent junction fragments identification by sequencing in 86% of cases (all deletion cases and 62.5% of duplication cases). Sequence examination of the junctions supports a role of microhomology-mediated processes in the occurrence of DMD large rearrangements. In addition, the precise knowledge of the sequence context at the breakpoints and analysis of the resulting consequences on maturation of pre-mRNA contribute to elucidating the cause of discrepancies in phenotype/genotype correlations in some patients. Thereby, the array-CGH proved to be a highly efficient and reliable diagnostic tool, and the new data it provides will have many potential implications in both, clinics and research.

The expanding spectrum of COL2A1 gene variants IN 136 patients with a skeletal dysplasia phenotype.

Heterozygous COL2A1 variants cause a wide spectrum of skeletal dysplasia termed type II collagenopathies. We assessed the impact of this gene in our French series. A decision tree was applied to select 136 probands (71 Stickler cases, 21 Spondyloepiphyseal dysplasia congenita cases, 11 Kniest dysplasia cases, and 34 other dysplasia cases) before molecular diagnosis by Sanger sequencing. We identified 66 different variants among the 71 positive patients. Among those patients, 18 belonged to multiplex families and 53 were sporadic. Most variants (38/44, 86%) were located in the triple helical domain of the collagen chain and glycine substitutions were mainly observed in severe phenotypes, whereas arginine to cysteine changes were more often encountered in moderate phenotypes. This series of skeletal dysplasia is one of the largest reported so far, adding 44 novel variants (15%) to published data. We have confirmed that about half of our Stickler patients (46%) carried a COL2A1 variant, and that the molecular spectrum was different across the phenotypes. To further address the question of genotype–phenotype correlation, we plan to screen our patients for other candidate genes using a targeted next-generation sequencing approach.

Myotonic dystrophy type 1 and PGD: ovarian stimulation response and correlation analysis between ovarian reserve and genotype.

This study aimed at evaluating parameters and results of ovarian stimulation for myotonic dystrophy type 1 (DM1) female patients undergoing preimplantation genetic diagnosis (PGD) and to assess an eventual association between genotype and ovarian reserve. A retrospective study involved all 17 DM1 patients treated in the study centres PGD programme. The control group consisted of 22 patients treated for X-linked disorders in the same period. Comparative analysis of ovarian stimulation parameters and results was performed with bivariate and multivariate analysis. Then, among DM1 patients, a correlation between genotype (number of CTG repeats) and ovarian reserve, assessed by antral follicle count, was investigated. Comparative study showed no difference concerning the number of oocytes, embryos and pregnancy rate between the two groups. Multivariate analysis demonstrated that DM1 patients needed a significantly higher dose of gonadotrophins (+544IU, P<0.001) than X-linked disorders patients and suggests a decreased ovarian sensitivity. However, with higher dose of gonadotrophins, PGD for DM1 offers good reproductive outcomes with a clinical pregnancy rate of 35.7%. Genotype was not correlated to ovarian reserve and appeared not to be helpful for the choice of the dose of gonadotrophins.

Identification of disrupted AUTS2 and EPHA6 genes by array painting in a patient carrying a de novo balanced translocation t(3;7) with intellectual disability and neurodevelopment disorder

Intellectual disability (ID) is a frequent feature but is highly clinically and genetically heterogeneous. The establishment of the precise diagnosis in patients with ID is challenging due to this heterogeneity but crucial for genetic counseling and appropriate care for the patients. Among the etiologies of patients with ID, apparently balanced de novo rearrangements represent 0.6%. Several mechanisms explain the ID in patients with apparently balanced de novo rearrangement. Among them, disruption of a disease gene at the breakpoint, is frequently evoked. In this context, technologies recently developed are used to characterize precisely such chromosomal rearrangements. Here, we report the case of a boy with ID, facial features and autistic behavior who is carrying a de novo balanced reciprocal translocation t(3;7)(q11.2;q11.22)dn. Using microarray analysis, array painting (AP) technology combined with molecular study, we have identified the interruption of the autism susceptibility candidate 2 gene (AUTS2) and EPH receptor A6 gene (EPHA6). We consider that the disruption of AUTS2 explains the phenotype of the patient; the exact role of EPHA6 in human pathology is not well defined. Based on the observation of recurrent germinal and somatic translocations involving AUTS2 and the molecular environment content, we put forward the hypothesis that the likely chromosomal mechanism responsible for the translocation could be due either to replicative stress or to recombination‐based mechanisms.

Is the early-onset torsion dystonia (EOTD) linked to TOR1A gene as frequent as expected in France?

Early onset torsion dystonia are rare movement disorders. Molecular defect is known for only a subgroup, consisting of a unique and recurrent mutation in the TOR1A gene. We undertook a nationwide census of French TOR1A-mutation carriers and the assessment of clinical associated signs. Overall, 53 index cases and 104 relatives were studied and haplotypes linked to the mutation constructed. The previously reported Ashkenazi-Jewish haplotype was found in 11 families with the remainder carrying distinct haplotypes suggesting independent mutation events. This study demonstrates the scarcity of this disease in France with estimated disease frequency of 0.13:100,000 and mutation frequency of 0.17:100,000.

Recurrent KIF2A mutations are responsible for classic lissencephaly

Kinesins play a critical role in the organization and dynamics of the microtubule cytoskeleton, making them central players in neuronal proliferation, neuronal migration, and postmigrational development. Recently, KIF2A mutations were identified in cortical malformation syndromes associated with microcephaly. Here, we detected two de novo p.Ser317Asn and p.His321Pro mutations in KIF2A in two patients with lissencephaly and microcephaly. In parallel, we re-evaluated the two previously reported cases showing de novo mutations of the same residues. The identification of mutations only in the residues Ser317 and His321 suggests these are hotspots for de novo mutations. Both mutations lead to a classic form of lissencephaly, with a posterior to anterior gradient, almost indistinguishable from LIS1-related lissencephaly. However, three fourths of patients also showed variable congenital and postnatal microcephaly, up to −5 SD. Located in the motor domain of the KIF2A protein, the Ser317 and His321 alterations are expected to disrupt binding or hydrolysis of ATP and consequently the MT depolymerizing activity. This report also establishes that KIF2A mutations represent significant causes of classic lissencephaly with microcephaly.