Sequencing of the GBA coactivator, Saposin C, in Parkinson disease

International audienceSaposin C (SapC), encoded by PSAP, is required for the activity of glucocerebrosidase, encoded by GBA. Although GBA mutations have been studied thoroughly in Parkinson disease (PD), genetic studies on SapC are still lacking. PSAP was sequenced in 1123 PD patients and 1153 controls, and data from additional 1167 patients and 1685 controls were examined. A total of 6 patients had SapC mutations in the 2 combined cohorts, but no statistically significant association after correction for multiple comparisons was found. Larger studies are necessary to examine the role of very rare SapC variants in P

Identification of a novel homozygous SPG7 mutation by whole exome sequencing in a Greek family with a complicated form of hereditary spastic paraplegia

We report the clinical description and genetic analyses of a Greek family with four individuals affected with a complicated form of hereditary spastic paraplegia (HSP) and a recessive pattern of inheritance. Exome sequencing of all affected individuals led to the identification of a homozygous 25 bp deletion predicted to lead to a frameshift and premature stop codon in the SPG7 gene, encoding paraplegin. This deletion, which is located in the first exon of the SPG7 gene, has not been previously reported and likely lead to the complete absence of the SPG7 protein. Interestingly, this family shows significant phenotypic heterogeneity further highlighting the clinical variability associated with SPG7 mutations. Our findings emphasize the clinical utility of whole exome sequencing for the molecular diagnosis of HSPs

Correction to: Exome sequencing reveals a novel PLP1 mutation in a Moroccan family with connatal Pelizaeus-Merzbacher disease: a case report

After publication of the original article [1] it was brought to our attention that author Bouchra Ouled Amar Bencheikh was incorrectly included as Bouchra Oulad Amar Bencheikh

Exome sequencing reveals a novel PLP1 mutation in a Moroccan family with connatal Pelizaeus-Merzbacher disease: a case report

Abstract Background Epilepsy regroups a common and diverse set of chronic neurological disorders that are characterized by spontaneous, unprovoked, and recurrent epileptic seizures. Epilepsies have a highly heterogeneous background with a strong genetic contribution and various mode of inheritance. X-linked epilepsy usually manifests as part of a syndrome or epileptic encephalopathy. The variability of clinical manifestations of X-linked epilepsy may be attributed to several factors including the causal genetic mutation, making diagnosis, genetic counseling and treatment decisions difficult. We report the description of a Moroccan family referred to our genetic department with X-linked epileptic seizures as the only initial diagnosis. Case presentation Knowing the new contribution of Next-Generation Sequencing (NGS) for clinical investigation, and given the heterogeneity of this group of disorders we performed a Whole-Exome Sequencing (WES) analysis and co-segregation study in several members of this large family. We detected a novel pathogenic PLP1 missense mutation c.251C > A (p.Ala84Asp) allowing us to make a diagnosis of Pelizaeus-Merzbacher Disease for this family. Conclusion This report extends the spectrum of PLP1 mutations and highlights the diagnostic utility of NGS to investigate this group of heterogeneous disorders

Common and rare GCH1 variants are associated with Parkinson's disease

International audienceGCH1 encodes the enzyme guanosine triphospahte (GTP) cyclohydrolase 1, essential for dopamine synthesis in nigrostriatal cells, and rare mutations in GCH1 may lead to Dopa-responsive dystonia (DRD). While GCH1 is implicated in genomewide association studies in Parkinson's disease (PD), only a few studies examined the role of rare GCH1 variants in PD, with conflicting results. In the present study, GCH1 and its 5' and 3' untranslated regions were sequenced in 1113 patients with PD and 1111 controls. To examine the association of rare GCH1 variants with PD, burden analysis was performed. Three rare GCH1 variants, which were previously reported to be pathogenic in DRD, were found in five patients with PD and not in controls (sequence Kernel association test, p = 0.024). A common haplotype, tagged by rs841, was associated with a reduced risk for PD (OR = 0.71, 95% CI = 0.61-0.83, p = 1.24 × 10-4), and with increased GCH1 expression in brain regions relevant for PD (www.gtexportal.org). Our results support a role for rare, DRD-related variants, and common GCH1 variants in the pathogenesis of PD

Routine Clinically Detected Increased ROS1 Transcripts Are Related With ROS1 Expression by Immunohistochemistry and Associated With EGFR Mutations in Lung Adenocarcinoma

Introduction: Translocations of the ROS1 gene were found to drive tumorigenesis in 1% to 2% of lung adenocarcinoma. In clinical practice, ROS1 rearrangements are often screened by immunohistochemistry (IHC) before confirmation with either fluorescence in situ hybridization or molecular techniques. This screening test leads to a non-negligible number of cases that have equivocal or positive ROS1 IHC, without ROS1 translocation. Methods: In this study, we have analyzed retrospectively 1021 cases of nonsquamous NSCLC having both ROS1 IHC and molecular analysis using next-generation sequencing. Results: ROS1 IHC was negative in 938 cases (91.9%), equivocal in 65 cases (6.4%), and positive in 18 cases (1.7%). Among these 83 equivocal or positive cases, only two were ROS1 rearranged, leading to a low predictive positive value of the IHC test (2%). ROS1-positive IHC was correlated with an increased mRNA ROS1 transcripts. Moreover, we have found a mean statistically significant relationship between ROS1 expression and EGFR gene mutations, suggesting a crosstalk mechanism between these oncogenic driver molecules. Conclusion: This study demonstrates that ROS1 IHC represents true ROS1 mRNA expression, and raises the question of a potential benefit of combined targeted therapy in EGFR-mutated NSCLC