ABSTRACT
BACKGROUND: The role of exosomes derived from HepG2.2.15 cells, which express hepatitis B virus (HBV)-related proteins, in triggering the activation of LX2 liver stellate cells and promoting liver fibrosis and cell proliferation remains elusive. The focus was on comprehending the relationship and influence of differentially expressed microRNAs (DE-miRNAs) within these exosomes. AIM: To elucidate the effect of exosomes derived from HepG2.2.15 cells on the activation of hepatic stellate cell (HSC) LX2 and the progression of liver fibrosis. METHODS: Exosomes from HepG2.2.15 cells, which express HBV-related proteins, were isolated from parental HepG2 and WRL68 cells. Western blotting was used to confirm the presence of the exosomal marker protein CD9. The activation of HSCs was assessed using oil red staining, whereas DiI staining facilitated the observation of exosomal uptake by LX2 cells. Additionally, we evaluated LX2 cell proliferation and fibrosis marker expression using 5-ethynyl-2'-deoxyuracil staining and western blotting, respectively. DE-miRNAs were analyzed using DESeq2. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were used to annotate the target genes of DE-miRNAs. RESULTS: Exosomes from HepG2.2.15 cells were found to induced activation and enhanced proliferation and fibrosis in LX2 cells. A total of 27 miRNAs were differentially expressed in exosomes from HepG2.2.15 cells. GO analysis indicated that these DE-miRNA target genes were associated with cell differentiation, intracellular signal transduction, negative regulation of apoptosis, extracellular exosomes, and RNA binding. KEGG pathway analysis highlighted ubiquitin-mediated proteolysis, the MAPK signaling pathway, viral carcinogenesis, and the toll-like receptor signaling pathway, among others, as enriched in these targets. CONCLUSION: These findings suggest that exosomes from HepG2.2.15 cells play a substantial role in the activation, proliferation, and fibrosis of LX2 cells and that DE-miRNAs within these exosomes contribute to the underlying mechanisms.
Subject(s)
Cell Proliferation , Exosomes , Hepatic Stellate Cells , Liver Cirrhosis , MicroRNAs , Humans , Exosomes/metabolism , Hepatic Stellate Cells/metabolism , Hepatic Stellate Cells/pathology , Hep G2 Cells , Liver Cirrhosis/pathology , Liver Cirrhosis/metabolism , Liver Cirrhosis/genetics , MicroRNAs/metabolism , MicroRNAs/genetics , Hepatitis B virus/genetics , Signal Transduction , Liver/pathology , Liver/metabolismABSTRACT
PURPOSE: Heterozygous variants in PRRT2 are mostly associated with benign phenotypes, being the major genetic cause of benign familial infantile seizures (BFIS), as well as in paroxysmal disorders. We report two children from unrelated families with BFIS that evolved to encephalopathy related to status epilepticus during sleep (ESES). METHODS AND RESULTS: Two probands presented with focal motor seizures at 3 months of age, with a limited course. Both children presented, at around 5 years of age, with centro-temporal interictal epileptiform discharges with a source in the frontal operculum, markedly activated by sleep, and associated with stagnation on neuropsychological development. Whole-exome sequencing and co-segregation analysis revealed a frameshift mutation c.649dupC in the proline-rich transmembrane protein 2 (PRRT2) in both probands and all affected family members. CONCLUSION: The mechanism leading to epilepsy and the phenotypic variability of PRRT2 variants remain poorly understood. However, its wide cortical and subcortical expression, in particular in the thalamus, could partially explain both the focal EEG pattern and the evolution to ESES. No variants in the PRRT2 gene have been previously reported in patients with ESES. Due to the rarity of this phenotype, other possible causative cofactors are likely contributing to the more severe course of BFIS in our probands.
Subject(s)
Epilepsy, Benign Neonatal , Status Epilepticus , Humans , Epilepsy, Benign Neonatal/complications , Epilepsy, Benign Neonatal/genetics , Membrane Proteins/genetics , Mutation/genetics , Nerve Tissue Proteins/genetics , Phenotype , Seizures/genetics , Seizures/complications , Status Epilepticus/geneticsABSTRACT
Schizophrenia is a disabling neuropsychiatric disorder of adulthood onset with high heritability. Worldwide collaborations have identified an association of ~270 common loci, with small individual effects and hence weak clinical implications. The recent technological feasibility of exome sequencing enables the identification of rare variants of high penetrance that refine previous findings and improve risk assessment and prognosis. We recruited two multiplex Pakistani families, having 11 patients and 19 unaffected individuals in three generations. We performed genome-wide SNP genotyping, next-generation mate pairing and whole-exome sequencing of selected members to unveil genetic components. Candidate variants were screened in unrelated cohorts of 508 cases, 300 controls and fifteen families (with 51 affected and 47 unaffected individuals) of Pakistani origin. The structural impact of substituted residues was assessed through in silico modeling using iTASSER. In one family, we identified a rare novel microduplication (5q14.1_q14.2) encompassing critical genes involved in glutamate signaling, such as CMYA5, HOMER and RasGRF2. The second family segregates two ultra-rare, predicted pathogenic variants in the GRIN2A (NM_001134407.3: c.3505C>T, (p.R1169W) and in the NRG3 NM_001010848.4: c.1951G>A, (p.E651K). These genes encode for parts of AMPA and NMDA receptors of glutamatergic neurotransmission, respectively, and the variants are predicted to compromise protein function by destabilizing their structures. The variants were absent in the aforementioned cohorts. Our findings suggest that rare, highly penetrant variants of genes involved in glutamatergic neurotransmission are contributing to the etiology of schizophrenia in these families. It also highlights that genetic investigations of multiplex, multigenerational families could be a powerful approach to identify rare genetic variants involved in complex disorders.
Subject(s)
Genetic Predisposition to Disease/genetics , Genetic Variation/genetics , Glutamic Acid/genetics , Schizophrenia/genetics , Signal Transduction/genetics , Synaptic Transmission/genetics , Adult , Exome/genetics , Female , Genome-Wide Association Study/methods , Humans , Male , Middle Aged , Pakistan , Pedigree , PenetranceABSTRACT
OBJECTIVE: To explore for the establishment of an experimental technique for profiling transcription factors, namely transcription factor response elements (TFRE), with high throughput and efficiency using human atrial tissue. METHODS: Postoperative right atrial tissues from 2 patients, one with preoperative atrial fibrillation and the one with no preoperative atrial fibrillation, were included in the study. The nucleus protein was extracted from the human atrial tissue, and the protein concentration was then measured. A solution with a complex formed through combining magnetic beads with concatenated tandem array of the consensus transcription factor response element DNA sequence (beads-catTFRE) was prepared, and the beads-catTFREs were then used to enrich transcription factors in the nucleoprotein extraction. SDS-PAGE electrophoresis was performed after dissociating beads-catTFRE from nucleoprotein with high temperature and high salt. The gel was then cut and faded before enzymolysis by trypsin in the gels was performed. Acetonitrile was used to extract the peptides from the gels, and the peptide solution was then dried. After that, we dissolved the peptides and performed mass spectrum tests, and the data were analyzed and processed with Firmiana one-stop proteomic analysis platform. RESULTS: In this study, 220 and 181 transcription factors were identified in the normal right atrial tissue and the right atrial tissue with atrial fibrillation, respectively. A total of 241 transcription factors were identified in the two groups. Among the 241 transcription factors, 12 were in the top 10% of those transcription factors that were above the median expression level of the normal right atrial tissue, and 12 transcription factors were in the top 10% of those above the median expression level of the right atrial tissue with atrial fibrillation. CONCLUSION: The high-throughput profiling method established in this study has high coverage, and the data collected can be used to support further validation studies.
Subject(s)
Atrial Fibrillation , Transcription Factors , Gene Expression Profiling , Gene Expression Regulation , Heart Atria , Humans , Proteomics , Transcription Factors/genetics , Transcription Factors/metabolismABSTRACT
OBJECTIVE: To study the effect of cytochrome P-4504F2 ( CYP4 F2) gene polymorphism on the initial dose of warfarin in patients after mechanical heart valve replacement. METHODS: We collected 350 patients receiving warfarin after mechanical heart valve replacement from January 2013 to December 2015 in our hospital. According to the international standardized ratio (INR) ≥2 at the initial stage after surgery, the patients were divided into two groups: INR≥2 group and INR<2 group. We selected the blood samples of all the 350 patients with testing the CYP4 F2 gene type of each patient, and analyzed the effect of CYP4 F2 gene polymorphism on the initial dose of warfarin after mechanical heart valve replacement (the average daily dose during hospitalization of patients 5-10 days after mechanical heart valve replacement). RESULTS: There was no statistical significance in the initial dose of warfarin among patients with different CYP4 F2 genotypes. However, warfarin dose was higher in CYP4 F2 TT genotype than in CYP4 F2 CC carriers ((3.37±0.68) mg vs. (2.94±0.74) mg, P<0.05) in INR≥2 group; In patients with the same genotype, the initial dose of warfarin in the CYP4 F2 CC ((4.02±0.58) mg vs. (2.94±0.74) mg) and CYP4 F2 CT genotypes ((4.15±0.88) mg vs. (3.18±0.82) mg) of INR<2 group was higher than that in INR≥2 group ( P<0.05). Gender, age, body mass index (BMI), comorbidities (hypertension, diabetes mellitus, coronary heart disease, atrial fibrillation), cytopigment P-450 2C9 ( CYP2 C9), CYP4 F2 and vitamin K peroxide-reductase complex 1 ( VKORC1) gene polymorphism and INR compliance were included in multiple linear regression analysis. The regression equation was as follows: warfarin initial dose (mg) =-8.634+0.352×BMI (kg/m 2) +1.102× CYP4 F2 genotype (CC or CT values 1, TT values 2) +2.147× VKORC1 (AA or AG values 1, GG values 2) +1.325×INR ( INR≥2 values 0, INR<2 values 1). The coefficient of determination ( R 2) of regression equation was 0.431 ( P<0.05). CONCLUSION: CYP4 F2 gene polymorphism may affect the initial dose of warfarin in patients after heart valve replacement, and this effect is also affected by body characteristics and other factors.
Subject(s)
Aryl Hydrocarbon Hydroxylases , Warfarin , Anticoagulants/therapeutic use , Aryl Hydrocarbon Hydroxylases/genetics , Cytochrome P-450 CYP2C9/genetics , Genotype , Heart Valves , Humans , International Normalized Ratio , Polymorphism, Genetic , Vitamin K Epoxide Reductases/genetics , Warfarin/therapeutic useABSTRACT
Primary microcephaly (MCPH) is characterized by reduced brain size and intellectual disability. The exact pathophysiological mechanism underlying MCPH remains to be elucidated, but dysfunction of neuronal progenitors in the developing neocortex plays a major role. We identified a homozygous missense mutation (p.W155C) in Ribosomal RNA Processing 7 Homolog A, RRP7A, segregating with MCPH in a consanguineous family with 10 affected individuals. RRP7A is highly expressed in neural stem cells in developing human forebrain, and targeted mutation of Rrp7a leads to defects in neurogenesis and proliferation in a mouse stem cell model. RRP7A localizes to centrosomes, cilia and nucleoli, and patient-derived fibroblasts display defects in ribosomal RNA processing, primary cilia resorption, and cell cycle progression. Analysis of zebrafish embryos supported that the patient mutation in RRP7A causes reduced brain size, impaired neurogenesis and cell proliferation, and defective ribosomal RNA processing. These findings provide novel insight into human brain development and MCPH.
Subject(s)
Cilia/metabolism , Microcephaly/genetics , Neurogenesis , Organelle Biogenesis , RNA-Binding Proteins/genetics , Ribosomes/metabolism , Adult , Animals , Base Sequence , Brain/embryology , Brain/pathology , Cell Cycle , Cell Nucleolus/metabolism , Centrosome/metabolism , Female , Fibroblasts/metabolism , Fibroblasts/pathology , Humans , Male , Mice , Mutation/genetics , Neural Stem Cells/metabolism , Nuclear Proteins/metabolism , Pakistan , Pedigree , Protein Binding , RNA Processing, Post-Transcriptional , RNA, Ribosomal/genetics , RNA-Binding Proteins/metabolism , Zebrafish/embryologyABSTRACT
BACKGROUND: In a Danish family, multiple individuals in five generations present with early-onset paroxysmal cranial dyskinesia, musculoskeletal abnormalities, and kidney dysfunction. OBJECTIVE: To demonstrate linkage and to identify the underlying genetic cause of disease. METHODS: Genome-wide single-nucleotide polymorphisms analysis, Sequence-Tagged-Site marker analyses, exome sequencing, and Sanger sequencing were performed. RESULTS: Linkage analyses identified a candidate locus on chromosome 9. Exome sequencing revealed a novel variant in LMX1B present in all affected individuals, logarithm of the odds (LOD) score of z = 6.54, predicted to be damaging. Nail-patella syndrome (NPS) is caused by pathogenic variants in LMX1B encoding a transcription factor essential to cytoskeletal and kidney growth and dopaminergic and serotonergic network development. NPS is characterized by abnormal musculoskeletal features and kidney dysfunction. Movement disorders have not previously been associated with NPS. CONCLUSIONS: Paroxysmal dyskinesia is a heretofore unrecognized feature of the NPS spectrum. The pathogenic mechanism might relate to aberrant dopaminergic circuits. © 2020 International Parkinson and Movement Disorder Society.
Subject(s)
Chorea , Nail-Patella Syndrome , Humans , LIM-Homeodomain Proteins/genetics , Nail-Patella Syndrome/genetics , Skull , Transcription Factors/geneticsABSTRACT
The 6%-9% risk of an untoward outcome previously established by Warburton for prenatally detected de novo balanced chromosomal rearrangements (BCRs) does not account for long-term morbidity. We performed long-term follow-up (mean 17 years) of a registry-based nationwide cohort of 41 individuals carrying a prenatally detected de novo BCR with normal first trimester screening/ultrasound scan. We observed a significantly higher frequency of neurodevelopmental and/or neuropsychiatric disorders than in a matched control group (19.5% versus 8.3%, p = 0.04), which was increased to 26.8% upon clinical follow-up. Chromosomal microarray of 32 carriers revealed no pathogenic imbalances, illustrating a low prognostic value when fetal ultrasound scan is normal. In contrast, mate-pair sequencing revealed disrupted genes (ARID1B, NPAS3, CELF4), regulatory domains of known developmental genes (ZEB2, HOXC), and complex BCRs associated with adverse outcomes. Seven unmappable autosomal-autosomal BCRs with breakpoints involving pericentromeric/heterochromatic regions may represent a low-risk group. We performed independent phenotype-aware and blinded interpretation, which accurately predicted benign outcomes (specificity = 100%) but demonstrated relatively low sensitivity for prediction of the clinical outcome in affected carriers (sensitivity = 45%-55%). This sensitivity emphasizes the challenges associated with prenatal risk prediction for long-term morbidity in the absence of phenotypic data given the still immature annotation of the morbidity genome and poorly understood long-range regulatory mechanisms. In conclusion, we upwardly revise the previous estimates of Warburton to a morbidity risk of 27% and recommend sequencing of the chromosomal breakpoints as the first-tier diagnostic test in pregnancies with a de novo BCR.
Subject(s)
Chromosome Aberrations , Prenatal Diagnosis/methods , Chromosome Breakpoints , Cohort Studies , Conserved Sequence/genetics , Evolution, Molecular , Female , Genome, Human , Humans , Karyotyping , Pregnancy , RNA, Long Noncoding/genetics , Risk Factors , Sequence Analysis, DNA , Time FactorsABSTRACT
CDK5RAP2 gene encodes a centrosomal protein, highly expressed in fetal brain and essentially indispensable for its normal development, as biallelic mutations in it lead to primary microcephaly (MCPH). Despite being known as MCPH linked gene for more than a decade, the phenotypic spectrum of CDK5RAP2 mutations is still under explored as only eleven families have been reported worldwide. Here, we analyzed a consanguineous Pakistani MCPH family, characterized by moderate to severe intellectual disability, speech impairment, moderately short stature and sparse eyebrows. Whole exome sequencing of the proband identified a 2bp duplication in exon 34 of CDK5RAP2 that causes frame-shift, leading to a premature stop codon. The resultant transcript is resistant to nonsense mediated decay, suggesting that the mutation leads to a truncated protein lacking C-terminal domains; CDK5R1, and Cnn motif 2 (CM2), required for its localization to centrosome and Golgi Apparatus. Clinical variability observed in the family highlights the importance of further detailed clinical description of patients with CDK5RAP2 mutations.
Subject(s)
Eyebrows/abnormalities , Frameshift Mutation , Intellectual Disability/genetics , Intracellular Signaling Peptides and Proteins/genetics , Microcephaly/genetics , Nerve Tissue Proteins/genetics , Speech Disorders/genetics , Adult , Cell Cycle Proteins , Child , Codon, Terminator/genetics , Consanguinity , Female , Humans , Intellectual Disability/diagnosis , Intracellular Signaling Peptides and Proteins/metabolism , Male , Microcephaly/diagnosis , Nerve Tissue Proteins/metabolism , Nonsense Mediated mRNA Decay , Pedigree , Speech Disorders/diagnosis , SyndromeABSTRACT
This study compares next-generation sequencing (NGS) technologies that have been optimized specifically for biofluid samples, with more established qPCR-based methods for profiling microRNAs in biofluids. The same patient serum samples were analyzed by NGS and qPCR, and differences in the serum microRNA profile between HBV and HCV infected patients were investigated. While there was overall good agreement between NGS and qPCR, there were some differences between the platforms, highlighting the importance of validation.
Subject(s)
Gene Expression Profiling/methods , High-Throughput Nucleotide Sequencing/methods , MicroRNAs/blood , MicroRNAs/genetics , Hepacivirus/isolation & purification , Hepatitis B/blood , Hepatitis B/genetics , Hepatitis B virus/isolation & purification , Hepatitis C/blood , Hepatitis C/genetics , Humans , Real-Time Polymerase Chain Reaction/methods , Reproducibility of ResultsABSTRACT
OBJECTIVE: To examine the role of mutations in GABRB3 encoding the ß3 subunit of the GABAA receptor in individual patients with epilepsy with regard to causality, the spectrum of genetic variants, their pathophysiology, and associated phenotypes. METHODS: We performed massive parallel sequencing of GABRB3 in 416 patients with a range of epileptic encephalopathies and childhood-onset epilepsies and recruited additional patients with epilepsy with GABRB3 mutations from other research and diagnostic programs. RESULTS: We identified 22 patients with heterozygous mutations in GABRB3, including 3 probands from multiplex families. The phenotypic spectrum of the mutation carriers ranged from simple febrile seizures, genetic epilepsies with febrile seizures plus, and epilepsy with myoclonic-atonic seizures to West syndrome and other types of severe, early-onset epileptic encephalopathies. Electrophysiologic analysis of 7 mutations in Xenopus laevis oocytes, using coexpression of wild-type or mutant ß3, together with α5 and γ2s subunits and an automated 2-microelectrode voltage-clamp system, revealed reduced GABA-induced current amplitudes or GABA sensitivity for 5 of 7 mutations. CONCLUSIONS: Our results indicate that GABRB3 mutations are associated with a broad phenotypic spectrum of epilepsies and that reduced receptor function causing GABAergic disinhibition represents the relevant disease mechanism.
Subject(s)
Epilepsy/genetics , Mutation , Receptors, GABA-A/genetics , Animals , Automation, Laboratory , Child , Child, Preschool , Cohort Studies , Epilepsy/physiopathology , Female , Heterozygote , High-Throughput Nucleotide Sequencing , Humans , Infant , Infant, Newborn , Male , Membrane Potentials/physiology , Oocytes , Patch-Clamp Techniques , Phenotype , Receptors, GABA-A/metabolism , Xenopus laevisABSTRACT
Split-hand/foot malformation 1 (SHFM1) is caused by chromosomal aberrations involving the region 7q21.3, DLX5 mutation, and dysregulation of DLX5/DLX6 expression by long-range position effects. SHFM1 can be isolated or syndromic with incomplete penetrance and a highly variable clinical expression, possibly influenced by sex and imprinting. We report on a new family with five affected individuals with syndromic SHFM1 that includes split-hand/foot malformations, hearing loss, and craniofacial anomalies, and an inv(7)(q21.3q35) present both in the proband and her affected son. The proximal inversion breakpoint, identified by next generation mate-pair sequencing, truncates the SHFM1 locus within the regulatory region of DLX5/6 expression. Through genotype-phenotype correlations of 100 patients with molecularly characterized chromosomal aberrations from 32 SHFM1 families, our findings suggest three phenotypic subregions within the SHFM1 locus associated with (1) isolated SHFM, (2) SHFM and hearing loss, and (3) SHFM, hearing loss, and craniofacial anomalies, respectively (ranked for increasing proximity to DLX5/6), and encompassing previously reported tissue-specific enhancers for DLX5/6. This uniquely well-characterized cohort of SHFM1 patients allowed us to systematically analyze the recently suggested hypothesis of skewed transmission and to confirm a higher penetrance in males vs. females in a subgroup of patients with isolated SHFM.
Subject(s)
Genetic Loci , Limb Deformities, Congenital/genetics , Phenotype , Proteasome Endopeptidase Complex/genetics , Adult , Amino Acid Sequence , Chromosome Inversion/genetics , Chromosomes, Human, Pair 7/genetics , Craniofacial Abnormalities/genetics , Female , Gene Expression Regulation , Genetic Association Studies , Hearing Loss/genetics , High-Throughput Nucleotide Sequencing , Homeodomain Proteins/genetics , Humans , Limb Deformities, Congenital/diagnosis , Logistic Models , Male , Molecular Sequence Data , Mutation , Pedigree , Transcription Factors/genetics , Young AdultSubject(s)
Carrier Proteins/genetics , Microcephaly/genetics , Mutation , RNA Splicing , Female , Humans , Male , Pakistan , PedigreeABSTRACT
OBJECTIVE: Benign familial infantile seizures (BFIS), paroxysmal kinesigenic dyskinesia (PKD), and their combination-known as infantile convulsions and paroxysmal choreoathetosis (ICCA)-are related autosomal dominant diseases. PRRT2 (proline-rich transmembrane protein 2 gene) has been identified as the major gene in all 3 conditions, found to be mutated in 80 to 90% of familial and 30 to 35% of sporadic cases. METHODS: We searched for the genetic defect in PRRT2-negative, unrelated families with BFIS or ICCA using whole exome or targeted gene panel sequencing, and performed a detailed cliniconeurophysiological workup. RESULTS: In 3 families with a total of 16 affected members, we identified the same, cosegregating heterozygous missense mutation (c.4447G>A; p.E1483K) in SCN8A, encoding a voltage-gated sodium channel. A founder effect was excluded by linkage analysis. All individuals except 1 had normal cognitive and motor milestones, neuroimaging, and interictal neurological status. Fifteen affected members presented with afebrile focal or generalized tonic-clonic seizures during the first to second year of life; 5 of them experienced single unprovoked seizures later on. One patient had seizures only at school age. All patients stayed otherwise seizure-free, most without medication. Interictal electroencephalogram (EEG) was normal in all cases but 2. Five of 16 patients developed additional brief paroxysmal episodes in puberty, either dystonic/dyskinetic or "shivering" attacks, triggered by stretching, motor initiation, or emotional stimuli. In 1 case, we recorded typical PKD spells by video-EEG-polygraphy, documenting a cortical involvement. INTERPRETATION: Our study establishes SCN8A as a novel gene in which a recurrent mutation causes BFIS/ICCA, expanding the clinical-genetic spectrum of combined epileptic and dyskinetic syndromes.
Subject(s)
Chorea/genetics , Epilepsy, Benign Neonatal/genetics , Genetic Predisposition to Disease/genetics , NAV1.6 Voltage-Gated Sodium Channel/genetics , Polymorphism, Single Nucleotide/genetics , Child , Child, Preschool , Chorea/diagnosis , Epilepsy, Benign Neonatal/diagnosis , Female , Humans , Male , Mutation/geneticsABSTRACT
OBJECTIVE: SCN8A encodes the sodium channel voltage-gated α8-subunit (Nav1.6). SCN8A mutations have recently been associated with epilepsy and neurodevelopmental disorders. We aimed to delineate the phenotype associated with SCN8A mutations. METHODS: We used high-throughput sequence analysis of the SCN8A gene in 683 patients with a range of epileptic encephalopathies. In addition, we ascertained cases with SCN8A mutations from other centers. A detailed clinical history was obtained together with a review of EEG and imaging data. RESULTS: Seventeen patients with de novo heterozygous mutations of SCN8A were studied. Seizure onset occurred at a mean age of 5 months (range: 1 day to 18 months); in general, seizures were not triggered by fever. Fifteen of 17 patients had multiple seizure types including focal, tonic, clonic, myoclonic and absence seizures, and epileptic spasms; seizures were refractory to antiepileptic therapy. Development was normal in 12 patients and slowed after seizure onset, often with regression; 5 patients had delayed development from birth. All patients developed intellectual disability, ranging from mild to severe. Motor manifestations were prominent including hypotonia, dystonia, hyperreflexia, and ataxia. EEG findings comprised moderate to severe background slowing with focal or multifocal epileptiform discharges. CONCLUSION: SCN8A encephalopathy presents in infancy with multiple seizure types including focal seizures and spasms in some cases. Outcome is often poor and includes hypotonia and movement disorders. The majority of mutations arise de novo, although we observed a single case of somatic mosaicism in an unaffected parent.
Subject(s)
Brain Diseases/genetics , Epilepsy/genetics , Mutation/genetics , NAV1.6 Voltage-Gated Sodium Channel/genetics , Phenotype , Adolescent , Brain Diseases/diagnosis , Brain Diseases/physiopathology , Child , Child, Preschool , Electroencephalography/methods , Epilepsy/diagnosis , Epilepsy/physiopathology , Female , Follow-Up Studies , Humans , Infant , Internationality , MaleABSTRACT
Genome instability, epigenetic remodelling and structural chromosomal rearrangements are hallmarks of cancer. However, the coordinated epigenetic effects of constitutional chromosomal rearrangements that disrupt genes associated with congenital neurodevelopmental diseases are poorly understood. To understand the genetic-epigenetic interplay at breakpoints of chromosomal translocations disrupting CG-rich loci, we quantified epigenetic modifications at DLGAP4 (SAPAP4), a key post-synaptic density 95 (PSD95) associated gene, truncated by the chromosome translocation t(8;20)(p12;q11.23), co-segregating with cerebellar ataxia in a five-generation family. We report significant epigenetic remodelling of the DLGAP4 locus triggered by the t(8;20)(p12;q11.23) translocation and leading to dysregulation of DLGAP4 expression in affected carriers. Disruption of DLGAP4 results in monoallelic hypermethylation of the truncated DLGAP4 promoter CpG island. This induced hypermethylation is maintained in somatic cells of carriers across several generations in a t(8;20) dependent-manner however, is erased in the germ cells of the translocation carriers. Subsequently, chromatin remodelling of the locus-perturbed monoallelic expression of DLGAP4 mRNAs and non-coding RNAs in haploid cells having the translocation. Our results provide new mechanistic insight into the way a balanced chromosomal rearrangement associated with a neurodevelopmental disorder perturbs allele-specific epigenetic mechanisms at breakpoints leading to the deregulation of the truncated locus.
Subject(s)
Cerebellar Ataxia/genetics , Chromatin Assembly and Disassembly , Epigenesis, Genetic , Nerve Tissue Proteins/genetics , Chromosomes, Human, Pair 8/genetics , CpG Islands , DNA Methylation , Female , Histones/genetics , Histones/metabolism , Humans , Male , Nerve Tissue Proteins/metabolism , RNA, Long Noncoding/genetics , RNA, Long Noncoding/metabolism , SAP90-PSD95 Associated Proteins , Translocation, GeneticABSTRACT
Genome-wide linkage analysis, followed by targeted deep sequencing, in a Danish multigeneration family with juvenile cataract revealed a region of chromosome 17 co-segregating with the disease trait. Affected individuals were heterozygous for two potentially protein-disrupting alleles in this region, in ACACA and UNC45B. As alterations of the UNC45B protein have been shown to affect eye development in model organisms, effort was focused on the heterozygous UNC45B missense mutation. UNC45B encodes a myosin-specific chaperone that, together with the general heat shock protein HSP90, is involved in myosin assembly. The mutation changes p.Arg805 to Trp in the UCS domain, an amino acid that is highly conserved from yeast to human. UNC45B is strongly expressed in the heart and skeletal muscle tissue, but here we show expression in human embryo eye and zebrafish lens. The zebrafish mutant steif, carrying an unc45b nonsense mutation, has smaller eyes than wild-type embryos and shows accumulation of nuclei in the lens. Injection of RNA encoding the human wild-type UNC45B protein into the steif homozygous embryo reduced the nuclei accumulation and injection of human mutant UNC45B cDNA in wild-type embryos resulted in development of a phenotype similar to the steif mutant. The p.Arg805Trp alteration in the mammalian UNC45B gene suggests that developmental cataract may be caused by a defect in non-muscle myosin assembly during maturation of the lens fiber cells.
Subject(s)
Cataract/genetics , Molecular Chaperones/genetics , Myosins/genetics , Acetyl-CoA Carboxylase/genetics , Acetyl-CoA Carboxylase/metabolism , Adolescent , Adult , Animals , Child , Chromosomes, Human, Pair 17 , Embryo, Nonmammalian , Gene Expression Regulation, Developmental , Genetic Loci , Genome-Wide Association Study , HSP90 Heat-Shock Proteins/genetics , HSP90 Heat-Shock Proteins/metabolism , Heterozygote , Homozygote , Humans , Immunohistochemistry , Lens, Crystalline/cytology , Lens, Crystalline/embryology , Lens, Crystalline/metabolism , Middle Aged , Molecular Chaperones/metabolism , Muscle Proteins , Muscle, Skeletal/metabolism , Mutation, Missense , Myosins/metabolism , Phenotype , Young Adult , Zebrafish/genetics , Zebrafish Proteins/genetics , Zebrafish Proteins/metabolismABSTRACT
PGAP2 encodes a protein involved in remodeling the glycosylphosphatidylinositol (GPI) anchor in the Golgi apparatus. After synthesis in the endoplasmic reticulum (ER), GPI anchors are transferred to the proteins and are remodeled while transported through the Golgi to the cell membrane. Germline mutations in six genes (PIGA, PIGL, PIGM, PIGV, PIGN, and PIGO) in the ER-located part of the GPI-anchor-biosynthesis pathway have been reported, and all are associated with phenotypes extending from malformation and lethality to severe intellectual disability, epilepsy, minor dysmorphisms, and elevated alkaline phosphatase (ALP). We performed autozygosity mapping and ultra-deep sequencing followed by stringent filtering and identified two homozygous PGAP2 alterations, p.Tyr99Cys and p.Arg177Pro, in seven offspring with nonspecific autosomal-recessive intellectual disability from two consanguineous families. Rescue experiments with the altered proteins in PGAP2-deficient Chinese hamster ovary cell lines showed less expression of cell-surface GPI-anchored proteins DAF and CD59 than of the wild-type protein, substantiating the pathogenicity of the identified alterations. Furthermore, we observed a full rescue when we used strong promoters before the mutant cDNAs, suggesting a hypomorphic effect of the mutations. We report on alterations in the Golgi-located part of the GPI-anchor-biosynthesis pathway and extend the phenotypic spectrum of the GPI-anchor deficiencies to isolated intellectual disability with elevated ALP. GPI-anchor deficiencies can be interpreted within the concept of a disease family, and we propose that the severity of the phenotype is dependent on the location of the altered protein in the biosynthesis chain.
Subject(s)
Glycosylphosphatidylinositols/genetics , Intellectual Disability/genetics , Mutation/genetics , Nuclear Proteins/genetics , Alkaline Phosphatase/blood , Amino Acid Sequence , Animals , Biological Transport , CHO Cells , Child , Child, Preschool , Cricetinae , Cricetulus , Endoplasmic Reticulum/metabolism , Female , Genes, Recessive , Golgi Apparatus/metabolism , Humans , Intellectual Disability/pathology , Lymphocytes/metabolism , Lymphocytes/pathology , Male , Molecular Sequence Data , Pedigree , Sequence Homology, Amino AcidABSTRACT
The finished human genome-assemblies comprise several hundred un-sequenced euchromatic gaps, which may be rich in long polypurine/polypyrimidine stretches. Human chromosome 20 (chr 20) currently has three unfinished gaps remaining on its q-arm. All three gaps are within gene-dense regions and/or overlap disease-associated loci, including the DLGAP4 locus. In this study, we sequenced â¼ 99% of all three unfinished gaps on human chr 20, determined their complete genomic sizes and assessed epigenetic profiles using a combination of Sanger sequencing, mate pair paired-end high-throughput sequencing and chromatin, methylation and expression analyses. We found histone 3 trimethylated at Lysine 27 to be distributed across all three gaps in immortalized B-lymphocytes. In one gap, five novel CpG islands were predominantly hypermethylated in genomic DNA from peripheral blood lymphocytes and human cerebellum. One of these CpG islands was differentially methylated and paternally hypermethylated. We found all chr 20 gaps to comprise structured non-coding RNAs (ncRNAs) and to be conserved in primates. We verified expression for 13 candidate ncRNAs, some of which showed tissue specificity. Four ncRNAs expressed within the gap at DLGAP4 show elevated expression in the human brain. Our data suggest that unfinished human genome gaps are likely to comprise numerous functional elements.
Subject(s)
Chromosomes, Human, Pair 20/chemistry , Chromosomes, Human, Pair 20/metabolism , Animals , Base Sequence , Cell Line , Conserved Sequence , CpG Islands , DNA Methylation , Histones/metabolism , Humans , Mice , Molecular Sequence Data , RNA, Untranslated/genetics , Sequence Analysis, DNAABSTRACT
In a monozygotic twin couple with mental retardation (MR), we identified a maternally inherited inversion and a paternally inherited translocation: 46,XY,inv(10)(p11.2q21.2)mat,t(9;18)(p22;q21.1)pat. The maternally inherited inv(10) was a benign variant without any apparent phenotypical implications. The translocation breakpoint at 9p was within a cluster of interferon α genes and the 18q21 breakpoint truncated ZBTB7C (zinc finger and BTB containing 7C gene). In addition, analyses with array-CGH revealed a 931 kb maternally inherited deletion on chromosome 8q22 as well as an 875 kb maternally inherited duplication on 5p14. The deletion encompasses the RIM2 (Rab3A-interacting molecule 2), FZD6 (Frizzled homolog 6) and BAALC (Brain and Acute Leukemia Gene, Cytoplasmic) genes and the duplication includes the 5' end of the CDH9 (cadherin 9) gene. Exome sequencing did not reveal any additional mutations that could explain the MR phenotype. The protein products of the above mentioned genes are involved in different aspects of brain development and/or maintenance of the neurons which suggest that accumulation of genetic defects segregating from both parents might be the basis of MR in the twins. This hypothesis was further supported by protein interaction analysis.