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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]

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]

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]

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]