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Biallelic disease‐causing variants in the ALPK3 gene were first identified in children presenting with a severe cardiomyopathy. More recently, it was shown that carriers of heterozygous ALPK3 null variants are at risk of developing hypertrophic cardiomyopathy (HCM) with an adult onset. Since the number of reported ALPK3 patients is small, the mutational spectrum and clinical data are not fully described. In this multi‐centric study, we described the molecular and clinical spectrum of a large cohort of ALPK3 patients. Genetic testing using targeted next generation sequencing was performed in 16 183 cardiomyopathy index cases. Thirty‐six patients carried at least one null ALPK3 variant. The five paediatric patients carried two ALPK3 variants, all presented an HCM phenotype with severe outcomes (one transplantation, one heart failure and one cardiac arrest). The 31 adult patients carried heterozygous variants and the main phenotype was HCM (n = 26/31); including 15% (n = 4) presented with an apical or a concentric form of hypertrophy. Reporting a large cohort of ALPK3 patients, this collaborative work confirmed a strong association with HCM and suggesting his screening in the context of idiopathic HCM. [ABSTRACT FROM AUTHOR]

Background and Objective: Pediatric cardiomyopathies are clinically heterogeneous heart muscle disorders associated with significant morbidity and mortality for which substantial evidence for a genetic contribution was previously reported. We present a detailed molecular investigation of a cohort of 231 patients presenting with primary cardiomyopathy below the age of 18 years. Methods: Cases with pediatric cardiomyopathies were analyzed using a next-generation sequencing (NGS) workflow based on a virtual panel including 57 cardiomyopathy-related genes. Results: This molecular approach led to the identification of 69 cases (29.9% of the cohort) genotyped as a carrier of at least one pathogenic or likely pathogenic variant. Fourteen patients were carriers of two mutated alleles (homozygous or compound heterozygous) on the same cardiomyopathy-related gene, explaining the severe clinical disease with early-onset cardiomyopathy. Homozygous TNNI3 pathogenic variants were detected for five unrelated neonates (2.2% of the cohort), with four of them carrying the same truncating variant, i.e. p.Arg69Alafs*8. Conclusions: Our study confirmed the importance of genetic testing in pediatric cardiomyopathies. Discovery of novel pathogenic variations is crucial for clinical management of affected families, as a positive genetic result might be used by a prospective parent for prenatal genetic testing or in the process of pre-implantation genetic diagnosis. [ABSTRACT FROM AUTHOR]

Amyotrophic Lateral Sclerosis (ALS) is a rare neurological disorder that causes degeneration of upper and lower motor neurons and their axons. ALS is mostly sporadic, but there are familial forms. In more than half of the familial forms, a pathogenic variant is found in one of the following genes: C9ORF72, SOD1, TDP-43, FUS, and VCP. SOD1 is the 2nd most common gene involved in genetic forms of ALS. Genotype–phenotype relationships are occasionally established in genetic forms of ALS associated with SOD1 mutations pathogenic variants. The c.281G > T (p.[G93V]) variant in SOD1 is associated with a rarely described and unexplained anticipation phenomenon. We report a large family from Martinique in whom ALS is associated with a c.281G > T (p.[G93V]) pathogenic variant in SOD1 and a statistically suggested anticipation. A whole-exome study and detection of CNVs (CoDESeq) from 3 affected members of this family revealed the presence of variants of uncertain signification (VUS) in other ALS genes. VUS in DCTN1 and NEFH were present in patients of the 2nd generation, and CNVs involving UBQLN2 and C21orf2 were found in the youngest case of the family. [ABSTRACT FROM AUTHOR]

The G4C2-repeat expansion in C9orf72 is the most common cause of frontotemporal dementia and of amyotrophic lateral sclerosis. The variability of age at onset and phenotypic presentations is a hallmark of C9orf72 disease. In this study, we aimed to identify modifying factors of disease onset in C9orf72 carriers using a family-based approach, in pairs of C9orf72 carrier relatives with concordant or discordant age at onset. Linkage and association analyses provided converging evidence for a locus on chromosome Xq27.3. The minor allele A of rs1009776 was associated with an earlier onset (P  = 1 × 10−5). The association with onset of dementia was replicated in an independent cohort of unrelated C9orf72 patients (P  = 0.009). The protective major allele delayed the onset of dementia from 5 to 13 years on average depending on the cohort considered. The same trend was observed in an independent cohort of C9orf72 patients with extreme deviation of the age at onset (P  = 0.055). No association of rs1009776 was detected in GRN patients, suggesting that the effect of rs1009776 was restricted to the onset of dementia due to C9orf72. The minor allele A is associated with a higher SLITRK2 expression based on both expression quantitative trait loci (eQTL) databases and in-house expression studies performed on C9orf72 brain tissues. SLITRK2 encodes for a post-synaptic adhesion protein. We further show that synaptic vesicle glycoprotein 2 and synaptophysin, two synaptic vesicle proteins, were decreased in frontal cortex of C9orf72 patients carrying the minor allele. Upregulation of SLITRK2 might be associated with synaptic dysfunctions and drives adverse effects in C9orf72 patients that could be modulated in those carrying the protective allele. How the modulation of SLITRK2 expression affects synaptic functions and influences the disease onset of dementia in C9orf72 carriers will require further investigations. In summary, this study describes an original approach to detect modifier genes in rare diseases and reinforces rising links between C9orf72 and synaptic dysfunctions that might directly influence the occurrence of first symptoms. [ABSTRACT FROM AUTHOR]

Objective: Mutations in superoxide dismutase 1 gene (SOD1), encoding copper/zinc superoxide dismutase protein, are the second most frequent high penetrant genetic cause for amyotrophic lateral sclerosis (ALS) motor neuron disease in populations of European descent. More than 200 missense variants are reported along the SOD1 protein. To limit the production of these aberrant and deleterious SOD1 species, antisense oligonucleotide approaches have recently emerged and showed promising effects in clinical trials. To offer the possibility to any patient with SOD1-ALS to benefit of such a gene therapy, it is necessary to ascertain whether any variant of unknown significance (VUS), detected for example in SOD1 non-coding sequences, is pathogenic.Methods: We analysed SOD1 mutation distribution after SOD1 sequencing in a large cohort of 470 French familial ALS (fALS) index cases.Results: We identified a total of 27 SOD1 variants in 38 families including two SOD1 variants located in nearsplice or intronic regions of the gene. The pathogenicity of the c.358-10T>G nearsplice SOD1 variant was corroborated based on its high frequency (as the second most frequent SOD1 variant) in French fALS, the segregation analysis confirmed in eight affected members of a large pedigree, the typical SOD1-related phenotype observed (with lower limb onset and prominent lower motor neuron involvement), and findings on postmortem tissues showing SOD1 misaccumulation.Conclusions: Our results highlighted nearsplice/intronic mutations in SOD1 are responsible for a significant portion of French fALS and suggested the systematic analysis of the SOD1 mRNA sequence could become the method of choice for SOD1 screening, not to miss these specific cases. [ABSTRACT FROM AUTHOR]

Background and objective: Molecular diagnosis in inherited cardiac diseases is challenging because of the significant genetic and clinical heterogeneity. We present a detailed molecular investigation of a cohort of 4185 patients with referrals for inherited cardiac diseases. Methods: Patients suffering from cardiomyopathies (3235 probands), arrhythmia syndromes (760 probands), or unexplained sudden cardiac arrest (190 cases) were analyzed using a next-generation sequencing (NGS) workflow based on a panel of 105 genes involved in sudden cardiac death. Results: (Likely) pathogenic variations were identified for approximately 30% of the cohort. Pathogenic copy number variations (CNVs) were detected in approximately 3.1% of patients for whom a (likely) pathogenic variation were identified. A (likely) pathogenic variation was also detected for 21.1% of patients who died from sudden cardiac death. Unexpected variants, including incidental findings, were present for 28 cases. Pathogenic variations were mainly observed in genes with definitive evidence of disease causation. Conclusions: Our study, which comprises over than 4000 probands, is one of most important cohorts reported in inherited cardiac diseases. The global mutation detection rate would be significantly increased by determining the putative pathogenicity of the large number of variants of uncertain significance. Identification of "unexpected" variants also showed the clinical utility of genetic testing in inherited cardiac diseases as they can redirect clinical management and medical resources toward a meaningful precision medicine. In cases with negative result, a WGS approach could be considered, but would probably have a limited impact on mutation detection rate as (likely) pathogenic variations were essentially clustered in genes with strong evidence of disease causation. [ABSTRACT FROM AUTHOR]

Mutations in the progranulin gene ( GRN) are an important cause of frontotemporal lobar degeneration (FTLD). Most known GRN mutations are null mutations, such as nonsense and frameshift mutations, which create a premature stop codon resulting in loss of function of the progranulin protein. Complete or near-complete genomic GRN deletions have also been found in three families, but heterozygous partial deletions that remove only one or two exons have not been reported to date. In this study, we analysed three unrelated FTLD patients with low plasma progranulin levels but no point GRN mutations by multiplex ligation-dependent probe amplification (MLPA) and quantitative multiplex polymerase chain reaction of short fluorescent fragments (QMPSF). We detected two heterozygous partial GRN deletions in two patients. One deletion removed exon 1 and part of intron 1. The second deletion was complex: it removed 1,410 bp extending from the part of intron 1 to the part of exon 3, with a small 5-bp insertion at the breakpoint junction (c.-7-1121_159delinsGATCA). Our findings illustrate the usefulness of a quantitative analysis in addition to GRN gene sequencing for a comprehensive genetic diagnosis of FTLD, particularly in patients with low plasma progranulin levels. [ABSTRACT FROM AUTHOR]

Mutations in SQSTM1 encoding the sequestosome 1/p62 protein have recently been identified in familial and sporadic cases of amyotrophic lateral sclerosis (ALS). p62 is a component of the ubiquitin inclusions detected in degenerating neurons in ALS patients. We sequenced SQSTM1 in 90 French patients with familial ALS (FALS) and 74 autopsied ALS cases with sporadic ALS (SALS). We identified, at the heterozygote state, one missense c.1175C>T, p.Pro392Leu (exon 8) in one of our FALS and one substitution in intron 7 (the c.1165+1G>A, previously called IVS7+1 G-A, A390X) affecting the exon 7 splicing site in one SALS. These mutations that are located in the ubiquitin-associated domain (UBA domain) of the p62 protein have already been described in Paget's disease and ALS patients carrying these mutations had both concomitant Paget's disease. However, we also identified two novel missense mutations in two SALS: the c.259A>G, p.Met87Val in exon 2 and the c.304A>G, p.Lys102Glu in exon 3. These mutations that were not detected in 360 control subjects are possibly pathogenic. Neuropathology analysis of three patients carrying SQSTM1 variants revealed the presence of large round p62 inclusions in motor neurons, and immunoblot analysis showed an increased p62 and TDP-43 protein levels in the spinal cord. Our results confirm that SQSTM1 gene mutations could be the cause or genetic susceptibility factor of ALS in some patients. [ABSTRACT FROM AUTHOR]

Objectives: To evaluate disease progression and determine validity of clinical tools for therapeutic trials. Design: Prospective cohort study (36 months). Setting: Referral center. Patients: One hundred sixty-two patients with autosomal dominant cerebellar ataxia and 64 with hereditary spastic paraplegia. Main Outcome Measures: The quantitative Composite Cerebellar Functional Severity Score with the writing test (CCFSw) and Scale for the Assessment and Rating of Ataxia (SARA) score. Results: Disease worsened in patients with SCA1, SCA2, and SCA3 mutations (mean [SE] increase in CCFSw, +0.014 [0.005] to +0.025 [0.004] per year), improved in patients with SPG4 mutations (mean [SE] increase in CCFSw, -0.012 [0.003] per year; P=.02), and remained stable in patients with SCA6, SCA7, or other SCA mutations (mean [SE] increase in CCFSw, -0.015 [0.011] to +0.009 [0.013] per year) or hereditary spastic paraplegia with other SPG mutations (mean [SE] increase in CCFSw, -0.005 [0.005] per year). Progression was faster in patients with SCA2 mutations and normal alleles with 22 or fewer repeats (P=.02) and in patients with SCA3 mutations with parkinsonism and/or dystonia at baseline (P=.003). Whereas CCFSw distinguished between patients with ataxia and spasticity, SARA scores increased in both groups. A 2-arm trial with SARA score as the outcome measure would require 57 patients with SCA2 mutations, 70 with SCA1 mutations, and 75 with SCA3 mutations per group to detect a 50% reduction in disease progression (power, 80%; α=.05). Conclusions: Disease progressed faster in SCAs with polyglutamine expansions in SCA1, 2, and 3 than the other groups. Both outcome measures are suitable for therapeutic trials; SARA requires fewer patients to attain the same power, but CCFSw needs less stratification. We demonstrate that the choice of clinical outcome measure is critical for reliable evaluation of progression in neurodegenerative diseases. [ABSTRACT FROM AUTHOR]

Background Expanded GGGGCC hexanucleotide repeats in the promoter of the C9ORF72 gene have recently been identified in frontotemporal dementia (FTD), Amyotrophic Lateral Sclerosis (ALS) and ALS-FTD and appear as the most common genetic cause of familial (FALS) and sporadic (SALS) forms of ALS. Methods We searched for the C9ORF72 repeat expansion in 950 French ALS patients (225 FALS and 725 SALS) and 580 control subjects and performed genotype-phenotype correlations. Results The repeat expansion was present in 46% of FALS, 8% of SALS and 0% of controls. Phenotype comparisons were made between FALS patients with expanded C9ORF72 repeats and patients carrying another ALS-related gene (SOD1, TARDBP, FUS) or a yet unidentified genetic defect. SALS patients with and without C9ORF72 repeat expansions were also compared. The C9ORF72 group presented more frequent bulbar onset both in FALS (p<0.0001 vs SOD1, p=0.002 vs TARDBP, p=0.011 vs FUS, p=0.0153 vs other FALS) and SALS (p=0.047). FALS patients with C9ORF72 expansions had more frequent association with FTD than the other FALS patients (p<0.0001 vs SOD1, p=0.04 vs TARDBP, p=0.004 vs FUS, p=0.03 vs other FALS). C9ORF72-linked FALS patients presented an older age of onset than SOD1 (p=0.0139) or FUS mutation (p<0.0001) carriers. Disease duration was shorter for C9ORF72 expansion carriers than for SOD1 (p<0.0001) and TARDBP (p=0.0242) carriers, other FALS (p<0.0001) and C9ORF72-negative SALS (p=0.0006). Conclusions Our results confirm the major role of expanded repeats in C9ORF72 as causative for ALS and provide evidence for specific phenotypic aspects compared to patients with other ALS-related genes. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Hereditary spastic paraplegias (HSP) constitute a heterogeneous group of neurodegenerative disorders characterized at least by slowly progressive spasticity of the lower limbs. Mutations in REEP1 were recently associated with a pure dominant HSP, SPG31. We sequenced all exons of REEP1 and searched for rearrangements by multiplex ligation-dependent probe amplification (MLPA) in a large panel of 175 unrelated HSP index patients from kindreds with dominant inheritance (AD-HSP), with either pure (n = 102) or complicated (n = 73) forms of the disease, after exclusion of other known HSP genes. We identified 12 different heterozygous mutations, including two exon deletions, associated with either a pure or a complex phenotype. The overall mutation rate in our clinically heterogeneous sample was 4.5% in French families with AD-HSP. The phenotype was restricted to pyramidal signs in the lower limbs in most patients but nine had a complex phenotype associating axonal peripheral neuropathy (= 5/11 patients) including a Silver-like syndrome in one patient, and less frequently cerebellar ataxia, tremor, dementia. Interestingly, we evidenced abnormal mitochondrial network organization in fibroblasts of one patient in addition to defective mitochondrial energy production in both fibroblasts and muscle, but whether these anomalies are directly or indirectly related to the mutations remains uncertain. Hum Mutat 32:1118-1127, 2011. ©2011 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

A K17I mutation in the ANG gene encoding angiogenin has been identified in a case that we previously published as ALS with neuronal intranuclear protein inclusions (Seilhean et al. in Acta Neuropathol 108:81–87, 2004). These inclusions were immunoreactive for smooth muscle α-actin but not for angiogenin. Moreover, they were not labeled by anti-TDP-43 antibodies, while numerous cytoplasmic inclusions immunoreactive for ubiquitin, p62 and TDP-43 were detected in both oligodendrocytes and neurons in various regions of the central nervous system. In addition, expression of smooth muscle α-actin was increased in the liver where severe steatosis was observed. This is the first neuropathological description of a case with an ANG mutation. Angiogenin is known to interact with actin. Like other proteins involved in ALS pathogenesis, such as senataxin, TDP-43 and FUS/TLS, it plays a role in RNA maturation. [ABSTRACT FROM AUTHOR]

PARK2 and PINK1 gene mutations are involved in recessive early onset Parkinson’s disease (EOPD). In order to determine the causative mutations in three affected sibs from a consanguineous Sudanese family with EOPD, multiplex ligation-dependent probe amplification was performed and revealed that the patients were homozygous for a deletion of PINK1 exons 4 to 8. Breakpoint analysis revealed a complex rearrangement combining a large deletion and the insertion of a sequence duplicated from the DDOST gene intron 2, located near the PINK1 gene. As breakpoint sequences displayed only three base pairs of homology, this rearrangement may result from Fork Stalling and Template Switching mechanism. This third large rearrangement of PINK1 enlarges the mutation spectrum and, together with recent published data in Tunisian patients with EOPD, points out that PINK1 gene analysis, including search for large rearrangement, should be considered in early onset recessive PD patients, particularly those from Arab origin. [ABSTRACT FROM AUTHOR]

Biallelic mutations in the CYP7B1 gene lead to spastic paraplegia-5 (SPG5). We report herein the case of a patient whose clinical symptoms began with progressive lower limb spasticity during childhood, and who secondly developed amyotrophic lateral sclerosis/frontotemporal dementia (ALS/FTD) at the age of 67 years. Hereditary spastic paraplegia (HSP) gene analysis identified the compound heterozygous mutations c.825T>A (pTyr275*) and c.1193C>T (pPro398Leu) in CYP7B1 gene. No other pathogenic variant in frequent ALS/FTD causative genes was found. The CYP7B1 gene seems, therefore, to be the third gene associated with the phenoconversion from HSP to ALS, after the recently described UBQLN2 and ERLIN2 genes. We therefore expand the phenotype associated with CYP7B1 biallelic mutations and make an assumption about a link between cholesterol dyshomeostasis and ALS/FTD. [ABSTRACT FROM AUTHOR]

Huntington's disease-like 2 (HDL2) is a neurodegenerative disorder found in people of African ancestry with clinical, radiological, and neuropathological manifestations similar to Huntington's disease (HD). HDL2 is caused by a pathological expansion of CAG/CTG triplets in exon 2A of the JPH3 gene. We describe four cases of HDL2 from four unrelated families, and discuss their clinical findings. HDL2 should be considered in every patient with an HD-like phenotype who tests negative for the HD mutation, even if African ancestry is not immediately apparent. © 2008 Movement Disorder Society [ABSTRACT FROM AUTHOR]

Background: Point mutations in SPG4, the gene encoding spastin, are a frequent cause of autosomal dominant hereditary spastic paraplegia (AD-HSP). However, standard methods for genetic analyses fail to detect exonic microdeletions. Methods: 121 mutation-negative probands were screened for rearrangements in SPG4 by multiplex ligation-dependent probe amplification. Results: 24 patients with 16 different heterozygotic exon deletions in SPG4 (20%) were identified, ranging from one exon to the whole coding sequence. Comparison with 78 patients with point mutations showed a similar clinical picture but an earlier age at onset. Conclusions: Exon deletions in SPG4 are as frequent as point mutations, and SPG4 is responsible for 40% of AD-HSP. [ABSTRACT FROM AUTHOR]

Seventy-nine unrelated Lebanese patients were tested for 15 mutations in the MEFV gene: A761H, A744S, V726A, K695R, M694V, M6941, M694del, M6801 (G→C), M6801 (G→A) in exon 10, F479L in exon 5, P369S in exon 3, T267I, E167D and E148Q in exon 2, using PCR digestion, ARMS, DGGE and/or sequencing. Mutations were detected in patients belonging to all communities, most interestingly the Maronite, Greek orthodox, Greek catholic, Syriac and Chiite communities. The most frequent mutations are M694V and V726A (27% and 20% of the total alleles respectively). M694I, E148Q and M6801 mutations account respectively for 9%, 8% and 5%. Each of the K695R, E167D and F479L mutations was observed once and all the remaining mutations were not encountered. Of the alleles 33% do not carry any of the studied mutations. The mutation spectra, clinical features and severity of the disease differed among the Lebanese communities. The genotype-phenotype analysis showed a significant association (P < 0.001) between amyloidosis and the presence of mutations at codon 694 in exon 10 (both M694V and M6941). None of the patients carrying other mutations developed amyloidosis. 51-55. [ABSTRACT FROM AUTHOR]

Background Mutations in SOD1, ANG, VAPB, TARDBP and FUS genes have been identified in amyotrophic lateral sclerosis (ALS). Methods The relative contributions of the different mutations to ALS were estimated by systematically screening a cohort of 162 families enrolled in France and 500 controls (1000 chromosomes) using molecular analysis techniques and performing phenotype-genotype correlations. Results 31 pathogenic missense mutations were found in 36 patients (20 SOD1, 1 ANG, 1 VAPB, 7 TARDBP and 7 FUS). Surprisingly two FUS mutation carriers also harboured ANG variants. One family of Japanese origin with the P56S VAPB mutation was identified. Seven novel mutations (three in SOD1, two in TARDBP, two in FUS) were found. None of them was detected in controls. Segregation of detected mutations with the disease was confirmed in 11 families including five pedigrees carrying the novel mutations. Clinical comparison of SOD1, TARDBP, FUS and other familial ALS patients (with no mutation in the screened genes) revealed differences in site of onset (predominantly lower limbs for SOD1 and upper limbs for TARDBP mutations), age of onset (younger with FUS mutations), and in lifespan (shorter for FUS carriers). One third of SOD1 patients survived more than 7 years: these patients had earlier disease onset than those presenting with a more typical course. Differences were also observed among FUS mutations, with the R521H FUS mutation being associated with longer disease duration. Conclusions This study identifies new genetic associations with ALS and provides phenotype-genotype correlations with both previously reported and novel mutations. [ABSTRACT FROM AUTHOR]