Familial adult myoclonus epilepsy (FAME) is a rare autosomal dominant disorder characterized by adult onset, involuntary muscle jerks, cortical myoclonus and occasional seizures. FAME is genetically ...heterogeneous with more than 70 families reported worldwide and five potential disease loci. The efforts to identify potential causal variants have been unsuccessful in all but three families. To date, linkage analysis has been the main approach to find and narrow FAME critical regions. We propose an alternative method, pedigree free identity-by-descent (IBD) mapping, that infers regions of the genome between individuals that have been inherited from a common ancestor. IBD mapping provides an alternative to linkage analysis in the presence of allelic and locus heterogeneity by detecting clusters of individuals who share a common allele. Succeeding IBD mapping, gene prioritization based on gene co-expression analysis can be used to identify the most promising candidate genes. We performed an IBD analysis using high-density single nucleotide polymorphism (SNP) array data followed by gene prioritization on a FAME cohort of ten European families and one Australian/New Zealander family; eight of which had known disease loci. By identifying IBD regions common to multiple families, we were able to narrow the FAME2 locus to a 9.78 megabase interval within 2p11.2–q11.2. We provide additional evidence of a founder effect in four Italian families and allelic heterogeneity with at least four distinct founders responsible for FAME at the FAME2 locus. In addition, we suggest candidate disease genes using gene prioritization based on gene co-expression analysis.
Abstract Mutations in OPTN gene encoding optineurin have recently been identified at the homozygote and heterozygote state in Japanese families with slowly progressive amyotrophic lateral sclerosis ...(ALS). OPTN had previously been involved in adult primary open angle glaucoma (POAG). We sequenced the coding exons of OPTN in 126 French patients with familial ALS (FALS). We identified, at the heterozygote state, the nonsense c.382_383insAG variant (also called 691_692insAG), alternatively reported as a causative mutation for primary open angle glaucoma (POAG) or a rare polymorphism and the new p.Arg96Leu variant in a family with dominant ALS. Western blot experiments on the patients' lymphoblasts showed that the former variant led to a loss of function and the latter did not cause protein accumulation. Our results do not confirm the contribution of OPTN in ALS.
Abstract Amyotrophic lateral sclerosis (ALS) is a devastating motor neuron disease including about 15% of genetically determined forms. A de novo mutation in the SS18L1 (also known as CREST or ...KIAA0693 ) gene encoding the calcium-responsive transactivator and/or neuronal chromatin remodeling complex subunit has recently been identified by exome sequencing of 47 sporadic ALS trios. This Q388stop mutation deleting the last 9 amino acids was shown to impair activity-dependent dendritic outgrowth. A missense mutation (c.369T>G, p.Ileu123Met) was also found in 1 of 62 ALS families previously screened for other ALS-related genes and not carrying any mutation. To confirm the contribution of SS18L1 to ALS, we sequenced the 11 coding exons and exon-intron boundaries in 87 familial ALS (FALS). We identified 2 variants: the c.660_668del, p.Gln222_Ser224del in a patient devoid of mutation in any ALS related genes and the c.790G>A, p.Ala264Thr in a patient carrying a p.Arg96Leu variant in the OPTN gene. As these variants were not found in Single Nucleotide Polymorphism databases and were absent from 180 controls they could be new SS18L1 mutations causing ALS.
Objective
DEPDC5 was identified as a major genetic cause of focal epilepsy with deleterious mutations found in a wide range of inherited forms of focal epilepsy, associated with malformation of ...cortical development in certain cases. Identification of frameshift, truncation, and deletion mutations implicates haploinsufficiency of DEPDC5 in the etiology of focal epilepsy. DEPDC5 is a component of the GATOR1 complex, acting as a negative regulator of mTOR signaling.
Methods
Zebrafish represents a vertebrate model suitable for genetic analysis and drug screening in epilepsy‐related disorders. In this study, we defined the expression of depdc5 during development and established an epilepsy model with reduced Depdc5 expression.
Results
Here we report a zebrafish model of Depdc5 loss‐of‐function that displays a measurable behavioral phenotype, including hyperkinesia, circular swimming, and increased neuronal activity. These phenotypic features persisted throughout embryonic development and were significantly reduced upon treatment with the mTORC1 inhibitor, rapamycin, as well as overexpression of human WT DEPDC5 transcript. No phenotypic rescue was obtained upon expression of epilepsy‐associated DEPDC5 mutations (p.Arg487* and p.Arg485Gln), indicating that these mutations cause a loss of function of the protein.
Interpretation
This study demonstrates that Depdc5 knockdown leads to early‐onset phenotypic features related to motor and neuronal hyperactivity. Restoration of phenotypic features by WT but not epilepsy‐associated Depdc5 mutants, as well as by mTORC1 inhibition confirm the role of Depdc5 in the mTORC1‐dependent molecular cascades, defining this pathway as a potential therapeutic target for DEPDC5‐inherited forms of focal epilepsy.
Autism spectrum disorders (ASD) and epilepsy frequently occur together. Prevalence rates are variable, and have been attributed to age, gender, comorbidity, subtype of pervasive developmental ...disorder (PDD) and risk factors. Recent studies have suggested disparate clinical and genetic settings depending on simplex or multiplex autism. The aim of this study was to assess: 1) the prevalence of epilepsy in multiplex autism and its association with genetic and non-genetic risk factors of major effect, intellectual disability and gender; and 2) whether autism and epilepsy cosegregate within multiplex autism families.
We extracted from the Autism Genetic Resource Exchange (AGRE) database (n = 3,818 children from 1,264 families) all families with relevant medical data (n = 664 children from 290 families). The sample included 478 children with ASD and 186 siblings without ASD. We analyzed the following variables: seizures, genetic and non-genetic risk factors, gender, and cognitive functioning as assessed by Raven's Colored Progressive Matrices (RCPM) and Vineland Adaptive Behavior Scales (VABS).
The prevalence of epilepsy was 12.8% in cases with ASD and 2.2% in siblings without ASD (P <10-5). With each RCPM or VABS measure, the risk of epilepsy in multiplex autism was significantly associated with intellectual disability, but not with gender. Identified risk factors (genetic or non-genetic) of autism tended to be significantly associated with epilepsy (P = 0.052). When children with prematurity, pre- or perinatal insult, or cerebral palsy were excluded, a genetic risk factor was reported for 6/59 (10.2%) of children with epilepsy and 12/395 (3.0%) of children without epilepsy (P = 0.002). Finally, using a permutation test, there was significant evidence that the epilepsy phenotype co-segregated within families (P <10-4).
Epilepsy in multiplex autism may define a different subgroup in terms of clinical characteristics and genetic risk.
ANXA11 mutations have previously been discovered in amyotrophic lateral sclerosis (ALS) motor neuron disease. To confirm the contribution of ANXA11 mutations to ALS, a large exome data set obtained ...from 330 French patients, including 150 familial ALS index cases and 180 sporadic ALS cases, was analyzed, leading to the identification of 3 rare ANXA11 variants in 5 patients. The novel p.L254V variant was associated with early onset sporadic ALS. The novel p.D40Y mutation and the p.G38R variant concerned patients with predominant pyramidal tract involvement and cognitive decline. Neuropathologic findings in a p.G38R carrier associated the presence of ALS typical inclusions within the spinal cord, massive degeneration of the lateral tracts, and type A frontotemporal lobar degeneration. This mutant form of annexin A11 accumulated in various brain regions and in spinal cord motor neurons, although its stability was decreased in patients' lymphoblasts. Because most ANXA11 inclusions were not colocalized with transactive response DNA-binding protein 43 or p62 deposits, ANXA11 aggregation does not seem mandatory to trigger neurodegeneration with additional participants/partner proteins that could intervene.
•Novel ANXA11 mutations are responsible for ALS.•ANXA11 mutations can be associated with early onset ALS and FTD.•Mutant G38 R ANXA11 is unstable in patient lymphoblasts.•Mutant G38 R ANXA11 led to cytoplasmic inclusions in post-mortem tissue.
Charcot-Marie-Tooth disease (CMT) comprises a clinically and genetically heterogeneous group of peripheral neuropathies characterized by progressive distal muscle weakness and atrophy, foot ...deformities and distal sensory loss. Following the analysis of two consanguineous families affected by a medium to late-onset recessive form of intermediate CMT, we identified overlapping regions of homozygosity on chromosome 1p36 with a combined maximum LOD score of 5.4. Molecular investigation of the genes from this region allowed identification of two homozygous mutations in PLEKHG5 that produce premature stop codons and are predicted to result in functional null alleles. Analysis of Plekhg5 in the mouse revealed that this gene is expressed in neurons and glial cells of the peripheral nervous system, and that knockout mice display reduced nerve conduction velocities that are comparable with those of affected individuals from both families. Interestingly, a homozygous PLEKHG5 missense mutation was previously reported in a recessive form of severe childhood onset lower motor neuron disease (LMND) leading to loss of the ability to walk and need for respiratory assistance. Together, these observations indicate that different mutations in PLEKHG5 lead to clinically diverse outcomes (intermediate CMT or LMND) affecting the function of neurons and glial cells.
A gene mutated in Charcot-Marie-Tooth disease type 4B (CMT4B), an autosomal recessive demyelinating neuropathy with myelin outfoldings, has been mapped on chromosome 11q22. Using a positional-cloning ...strategy, we identified in unrelated CMT4B patients mutations occurring in the gene MTMR2, encoding myotubularin-related protein-2, a dual specificity phosphatase (DSP).
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
To describe the clinical and electrophysiological features evoking CMT4C, an autosomal recessive (AR) form of Charcot‐Marie‐Tooth disease (CMT) due to mutations in the SH3TC2 gene, we screened the ...coding sequence of SH3TC2 gene in 102 unrelated patients with a demyelinating or intermediate CMT and a family history compatible with an AR transmission. We identified among this cohort 16 patients carrying two mutations in the SH3TC2 gene, but medical records finally analyzed 14 patients. We report clinical, electrophysiological, and molecular data of 14 patients (9 men, 5 women) with CMT4C. Mean age at examination was 43.6 years (median = 42.5). Among the 14 studied cases 6 had scoliosis as the presenting sign. Cranial nerve involvement affecting either the VIIIth, VIIth, XIIth or a combination of the IXth and Xth nerves was noted in 10 patients. Remarkably, 50% of the patients had proximal limb involvement at the time of examination. The hallmark of the electrophysiological study was the presence of probable conduction block and temporal dispersion. Thus the clinical and paraclinical spectrum of CMT4C can guide the clinician to perform analysis of the SH3TC2 gene.
Eleven samples of DNA from choriocarcinomas were studied by high resolution CGH-array 244 K. They were studied after histopathological confirmation of the diagnosis, of the androgenic etiology and ...after a microsatellite marker analysis confirming the absence of contamination of tumor DNA from maternal DNA. Three cell lines, BeWo, JAR, JEG were also studied by this high resolution pangenomic technique. According to aCGH analysis, the de novo choriocarcinomas exhibited simple chromosomal rearrangements or normal profiles. The cell lines showed various and complex chromosomal aberrations. 23 Minimal Critical Regions were defined that allowed us to list the genes that were potentially implicated. Among them, unusually high numbers of microRNA clusters and imprinted genes were observed.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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