Identification of subtelomeric genomic imbalances and breakpoint mapping with quantitative PCR in 296 individuals with congenital defects and/or mental retardation

<p>Abstract</p> <p>Background</p> <p>Submicroscopic imbalances in the subtelomeric regions of the chromosomes are considered to play an important role in the aetiology of mental retardation (MR). The aim of the study was to evaluate a quantitative PCR (qPCR) protocol established by Boehm et al. (2004) in the clinical routine of subtelomeric testing.</p> <p>Results</p> <p>296 patients with MR and a normal karyotype (500–550 bands) were screened for subtelomeric imbalances by using qPCR combined with SYBR green detection. In total, 17 patients (5.8%) with 20 subtelomeric imbalances were identified. Six of the aberrations (2%) were classified as causative for the symptoms, because they occurred either <it>de novo </it>in the patients (5 cases) or the aberration were be detected in the patient and an equally affected parent (1 case). The extent of the deletions ranged from 1.8 to approximately 10 Mb, duplications were 1.8 to approximately 5 Mb in size. In 6 patients, the copy number variations (CNVs) were rated as benign polymorphisms, and the clinical relevance of these CNVs remains unclear in 5 patients (1.7%). Therefore, the overall frequency of clinically relevant imbalances ranges between 2% and 3.7% in our cohort.</p> <p>Conclusion</p> <p>This study illustrates that the qPCR/SYBR green technique represents a rapid and versatile method for the detection of subtelomeric imbalances and the option to map the breakpoint. Thus, this technique is highly suitable for genotype/phenotype studies in patients with MR/developmental delay and/or congenital defects.</p

Generation of homozygous Nav_{v}1.8 knock-out iPSC lines by CRISPR Cas9 genome editing to investigate a potential new antiarrhythmic strategy

The sodium channel Na$_{v}$1.8, encoded by SCN10A, is reported to contribute to arrhythmogenesis by inducing the late I$_{Na}$ and thereby enhanced persistent Na$^{+}$ current. However, its exact electrophysiological role in cardiomyocytes remains unclear. Here, we generated induced pluripotent stem cells (iPSCs) with a homozygous SCN10A knock-out from a healthy iPSC line by CRISPR Cas9 genome editing. The edited iPSCs maintained full pluripotency, genomic integrity, and spontaneous in vitro differentiation capacity. The iPSCs are able to differentiate into iPSC-cardiomyocytes, hence making it possible to investigate the role of Na$_{v}$1.8 in the heart

Generation of homozygous Nav1.8 knock-out iPSC lines by CRISPR Cas9 genome editing to investigate a potential new antiarrhythmic strategy

The sodium channel Na(v)1.8, encoded by SCN10A, is reported to contribute to arrhythmogenesis by inducing the late INa and thereby enhanced persistent Na+ current. However, its exact electrophysiological role in cardiomyocytes remains unclear. Here, we generated induced pluripotent stem cells (iPSCs) with a homozygous SCN10A knock-out from a healthy iPSC line by CRISPR Cas9 genome editing. The edited iPSCs maintained full pluripotency, genomic integrity, and spontaneous in vitro differentiation capacity. The iPSCs are able to differentiate into iPSC-cardiomyocytes, hence making it possible to investigate the role of Na(v)1.8 in the heart

Generation and cardiac differentiation of an induced pluripotent stem cell line from a patient with arrhythmia-induced cardiomyopathy

Arrhythmia-induced cardiomyopathy (AIC) is characterized by left-ventricular systolic dysfunction caused by persistent arrhythmia. To date, genetic or pathological drivers causing AIC remain unknown. Here, we generated induced pluripotent stem cells (iPSCs) from an AIC patient. The AIC-iPSCs exhibited full pluripotency and differentiation characteristics and maintained a normal karyotype after reprogramming. The AIC-iPSCs differentiated into functional beating AIC-iPSCcardiomyocytes (CMs), which represents the cell-type of interest to study molecular, genetic and functional aspects of AIC

CARASIL with coronary artery disease and distinct cerebral microhemorrhage: A case report and literature review

Cerebral Autosomal Recessive Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CARASIL, Maeda syndrome) is an extremely rare autosomal-recessive genetic disorder with a serious arteriopathy causing subcortical infarcts and leukoencephalopathy. In less than 20 cases, a genetic mutation was proven. Patients suffer from alopecia, disc herniations, and spondylosis. Between the age of 30 and 40, the patients typically develop severe cerebral infarcts. Clinical symptoms, genetic study, magnetic resonance imaging (MRI), and coronary angiography of a patient with proven CARASIL are presented. The patient showed the typical phenotype with cerebral small-vessel disease, cerebral infarcts, spondylosis, and abnormal hair loss. Additionally, distinct cerebral microhemorrhage and a severe coronary artery disease (CAD) were found, which have not been reported before for CARASIL. Mutation screening revealed the presence of a homozygous c.1022G > T substitution in the HTRA1 gene. Evidence from other publications supports a pathogenetic link between the HTRA1 mutation and CAD as a new feature of CARASIL. This is the first report about CARASIL with a concomitant severe CAD. Thus, in patients with CARASIL, other vessel diseases should also be considered

Bi-allelic missense disease-causing variants in RPL3L associate neonatal dilated cardiomyopathy with muscle-specific ribosome biogenesis

Dilated cardiomyopathy (DCM) belongs to the most frequent forms of cardiomyopathy mainly characterized by cardiac dilatation and reduced systolic function. Although most cases of DCM are classified as sporadic, 20-30% of cases show a heritable pattern. Familial forms of DCM are genetically heterogeneous, and mutations in several genes have been identified that most commonly play a role in cytoskeleton and sarcomere-associated processes. Still, a large number of familial cases remain unsolved. Here, we report five individuals from three independent families who presented with severe dilated cardiomyopathy during the neonatal period. Using whole-exome sequencing (WES), we identified causative, compound heterozygous missense variants in RPL3L (ribosomal protein L3-like) in all the affected individuals. The identified variants co-segregated with the disease in each of the three families and were absent or very rare in the human population, in line with an autosomal recessive inheritance pattern. They are located within the conserved RPL3 domain of the protein and were classified as deleterious by several in silico prediction software applications. RPL3L is one of the four non-canonical riboprotein genes and it encodes the 60S ribosomal protein L3-like protein that is highly expressed only in cardiac and skeletal muscle. Three-dimensional homology modeling and in silico analysis of the affected residues in RPL3L indicate that the identified changes specifically alter the interaction of RPL3L with the RNA components of the 60S ribosomal subunit and thus destabilize its binding to the 60S subunit. In conclusion, we report that bi-allelic pathogenic variants in RPL3L are causative of an early-onset, severe neonatal form of dilated cardiomyopathy, and we show for the first time that cytoplasmic ribosomal proteins are involved in the pathogenesis of non-syndromic cardiomyopathies

Expansion of mutation spectrum, determination of mutation cluster regions and predictive structural classification of SPAST mutations in hereditary spastic paraplegia

The SPAST gene encoding for spastin plays a central role in the genetically heterogeneous group of diseases termed hereditary spastic paraplegia (HSP). In this study, we attempted to expand and refine the genetic and phenotypic characteristics of SPAST associated HSP by examining a large cohort of HSP patients/families. Screening of 200 unrelated HSP cases for mutations in the SPAST gene led to detection of 57 mutations (28.5%), of which 47 were distinct and 29 were novel mutations. The distribution analysis of known SPAST mutations over the structural domains of spastin led to the identification of several regions where the mutations were clustered. Mainly, the clustering was observed in the AAA (ATPases associated with diverse cellular activities) domain; however, significant clustering was also observed in the MIT (microtubule interacting and trafficking), MTBD (microtubule-binding domain) and an N-terminal region (228–269 residues). Furthermore, we used a previously generated structural model of spastin as a framework to classify the missense mutations in the AAA domain from the HSP patients into different structural/functional groups. Our data also suggest a tentative genotype–phenotype correlation and indicate that the missense mutations could cause an earlier onset of the disease