👤 Sean Lal

To characterise severe hypertriglyceridaemia (HTG) in Indian children, focusing on clinical and genetic profiles. A retrospective analysis from January 2017 to December 2023 included children up to 14 years old with triglyceride (TG) levels > 500 mg/dl, excluding children with known secondary causes. Among 18 children with severe HTG, 7 had secondary causes. Data from 11 patients (7 boys, median age at diagnosis 0.9 [0.45-2.4] years) revealed presenting features such as lipemic serum (63.3%), failure to thrive (36.3%), loss of subcutaneous fat (18.2%), and abdominal distension (18.2%). Genetic aetiology was identified in 10 cases, with familial chylomicronaemia syndrome (FCS) being the most prevalent (6 cases) caused by the lipoprotein lipase (LPL) and apolipoprotein A-V (APOA5) gene mutations. One each had mutations in the 1-acylglycerol-3-phosphate O-acyltransferase 2 (AGPAT2), lamin A/C (LMNA), glucose-6-phosphatase catalytic subunit (G6PC), and glycerol kinase (GK) genes. FCS patients presented earlier and were resistant to treatment targets, requiring drug therapy. At the final follow-up (mean duration 1.75 ±1.0 years) of 9 patients, the median TG levels for the FCS and non-FCS groups were 1240 (610-1,685) and 412 (247.5-993) mg/dl, respectively. Only 2 patients (40%) with FCS had TG levels < 1000 mg/dl, while all but one (75%) non-FCS subjects had TG levels < 500 mg/dl at the last follow-up. One child developed acute pancreatitis during the said duration. Paediatric HTG is often detected incidentally. Genetic characterisation is crucial for prognosis because baseline TG levels are non-predictive. Drug therapy helps to reach treatment targets in most of the patients. Show less

Hypertrophic cardiomyopathy (HCM) is a prevalent inherited cardiac disorder marked by left ventricular hypertrophy and hypercontractility. This excessive mechanical workload creates an energetic mismatch in which consumption exceeds production, leading to myocardial energy depletion. Although CK (creatine kinase) plays a key role in cardiac energy homeostasis, its involvement in HCM remains unclear. This study investigates how hypercontractility-driven mitochondrial stress and the resulting increase in mitochondrial H CK function was analyzed using myocardial left ventricular tissue from 92 patients with HCM (with and without pathogenic sarcomere variants) and 30 non-failing human controls. Myofilament and mitochondrial CK isoforms were measured using mRNA analysis, protein immunoblotting, enzyme activity assays, mass spectrometry, and redox-sensitive proteomics. To explore links between hypercontractility, mitochondrial reactive oxygen species, and CK dysfunction, we used isolated cardiomyocytes from wild-type, mitochondrial-targeted catalase-overexpressing, CK knockout (myofilament and mitochondrial CK deletion), HCM-associated Our analysis revealed significant reductions in myofilament and mitochondrial CK protein levels, as well as CK activity, in myocardium of patients with HCM, primarily because of oxidative modifications of CK. In isolated mouse cardiomyocytes from wild-type and CK knockouts, hypercontractility induced by EMD-57033 elevated mitochondrial H This study reveals a mechanistic link between hypercontractility, mitochondrial reactive oxygen species, and CK dysfunction in HCM, perpetuating a cycle of energetic dysfunction. Targeting hypercontractility and oxidative stress through myosin inhibition offers a strategy to restore energy balance and reduce arrhythmic risk in HCM. Show less

Lesional focal epilepsy (LFE) is a common and severe seizure disorder caused by epileptogenic lesions, including malformations of cortical development (MCD) and low-grade epilepsy-associated tumors (LEAT). Understanding the genetic etiology of these lesions can inform medical and surgical treatment. We conducted a somatic variant enrichment mega-analysis in brain tissue from 1386 individuals who underwent epilepsy surgery, including 599 previously unpublished individuals with ultra-deep ( > 1600x) targeted panel sequencing. Here we confirm four known associations (BRAF, SLC35A2, MTOR, PTPN11), support eight associations without prior statistical support (FGFR1, PIK3CA, AKT3, NF1, PTEN, RHEB, KRAS, NRAS), and identify novel associations for two genes, DYRK1A and EGFR. Both novel genes show specific histopathological phenotypes, interact with LFE genes and pathways, and may represent promising candidates as biomarkers and potentially druggable targets. Show less

In this study, comparative analysis of skeletal muscle transcriptome was carried out for four biological replicates of Aseel, a fighter type breed and Punjab Brown, a meat type breed of India. The profusely expressed genes in both breeds were related to muscle contraction and motor activity. Differential expression analysis identified 961 up-regulated and 979 down-regulated genes in Aseel at a threshold of log Show less

There is an incomplete understanding of the burden of splice-disrupting variants in definitively associated inherited heart disease genes and whether these genes can amplify from blood RNA to support functional confirmation of splicing outcomes. We performed burden testing of rare splice-disrupting variants in people with inherited heart disease and sudden unexplained death compared to 125,748 population controls. ClinGen definitively disease-associated inherited heart disease genes were amplified using RNA extracted from fresh blood, derived cardiomyocytes, and myectomy tissue. Variants were functionally assessed and classified for pathogenicity. We found 88 in silico-predicted splice-disrupting variants in 128 out of 1242 (10.3%) unrelated participants. There was an excess burden of splice-disrupting variants in PKP2 (5.9%), FLNC (2.7%), TTN (2.8%), MYBPC3 (8.2%) and MYH7 (1.3%), in distinct cardiomyopathy subtypes, and KCNQ1 (3.6%) in long QT syndrome. Blood RNA supported the amplification of 21 out of 31 definitive disease-associated inherited heart disease genes. Our functional studies confirmed altered splicing in six variants. Eleven variants of uncertain significance were reclassified as likely pathogenic based on functional studies and six were used for cascade genetic testing in 12 family members. Our study highlights that splice-disrupting variants are a significant cause of inherited heart disease, and that analysis of blood RNA confirms splicing outcomes and supports variant pathogenicity classification. Show less

Hypertrophic cardiomyopathy (HCM) is the most prevalent inherited cardiac disease. Up to 40% of cases are associated with heterozygous mutations in myosin binding protein C (cMyBP-C, MYBPC3). Most of these mutations lead to premature termination codons (PTC) and patients show reduction of functional cMyBP-C. This so-called haploinsufficiency most likely contributes to disease development. We analyzed mechanisms underlying haploinsufficiency using cardiac tissue from HCM-patients with truncation mutations in MYBPC3 (MYBPC3 Show less

Transcriptome sequencing can improve genetic diagnosis of Mendelian diseases but requires access to tissue expressing disease-relevant transcripts. We explored genetic testing of hypertrophic cardiomyopathy using transcriptome sequencing of patient-specific human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs). We also explored whether antisense oligonucleotides (AOs) could inhibit aberrant mRNA splicing in hiPSC-CMs. We derived hiPSC-CMs from patients with hypertrophic cardiomyopathy due to Transcriptome sequencing of hiPSC-CMs confirmed aberrant splicing in 2 people with previously identified Transcriptome sequencing of patient specific hiPSC-CMs solved a previously undiagnosed genetic cause of hypertrophic cardiomyopathy and may be a useful adjunct approach to genetic testing. Antisense oligonucleotide inhibition of cryptic exon splicing is a potential future personalized therapeutic option. Show less

Inflammatory processes play an important role in the pathogenesis of glomerulopathies. Finding novel ways to suppress glomerular inflammation may offer a new way to stop disease progression. However, the molecular mechanisms that initiate and drive inflammation in the glomerulus are still poorly understood. We performed large-scale gene expression profiling of glomerulus-associated G protein-coupled receptors (GPCRs) to identify new potential therapeutic targets for glomerulopathies. The expression of Gprc5b in disease was analyzed using quantitative PCR and immunofluorescence, and by analyzing published microarray data sets. We identified an orphan GPCR, Gprc5b, as a novel gene highly enriched in podocytes that was significantly upregulated in common human glomerulopathies, including diabetic nephropathy, IgA nephropathy, and lupus nephritis. Similar upregulation of Gprc5b was detected in LPS-induced nephropathy in mice. Studies in podocyte-specific Gprc5b knockout mice showed that Gprc5b was not essential for normal development of the glomerular filtration barrier. However, knockout mice were partially protected from LPS-induced proteinuria and recruitment of inflammatory cells. Mechanistically, RNA sequencing in Gprc5b knockouts mice and experiments in cultured human podocytes showed that Gpr5cb regulated inflammatory response in podocytes GPRC5b is a novel podocyte-specific receptor that regulates inflammatory response in the glomerulus by modulating the NF- Show less

KANSL1 haploinsufficiency causes Koolen-de Vries syndrome (KdVS), characterized by dysmorphic features and intellectual disability; amiable personality, congenital malformations and seizures also commonly occur. The epilepsy phenotypic spectrum in KdVS is broad, but most individuals have focal seizures with some having a phenotype resembling the self-limited focal epilepsies of childhood (SFEC). We hypothesized that variants in KANSL1 contribute to pathogenesis of SFEC. We screened KANSL1 for single nucleotide variants in 90 patients with SFEC. We then screened a cohort of 208 patients with two specific SFEC syndromes, childhood epilepsy with centrotemporal spikes (CECTS) and atypical childhood epilepsy with centrotemporal spikes (ACECTS) for KANSL1 variants. The second cohort was also used to evaluate minor allelic variants that appeared overrepresented in the initial cohort. One variant, p.Lys104Thr, was predicted damaging and appeared overrepresented in our 90-patient cohort compared to Genome Aggregation Database (gnomAD) allele frequency (0.217 to 0.116, with no homozygotes in gnomAD). However, there was no difference in p.Lys104Thr allele frequency in the follow-up CECTS/ACECTS cohort and controls. Four rare KANSL1 variants of uncertain significance were identified in the CECTS/ACECTS cohort. Our data do not support a major role for KANSL1 variants in pathogenesis of SFEC. Show less

The "super-relaxed state" (SRX) of myosin represents a 'reserve' of motors in the heart. Myosin heads in the SRX are bound to the thick filament and have a very low ATPase rate. Changes in the SRX are likely to modulate cardiac contractility. We previously demonstrated that the SRX is significantly reduced in mouse cardiomyocytes lacking cardiac myosin binding protein-C (cMyBP-C). Here, we report the effect of mutations in the cMyBP-C gene (MYBPC3) using samples from human patients with hypertrophic cardiomyopathy (HCM). Left ventricular (LV) samples from 11 HCM patients were obtained following myectomy surgery to relieve LV outflow tract obstruction. HCM samples were genotyped as either MYBPC3 mutation positive (MYBPC3mut) or negative (HCMsmn) and were compared to eight non-failing donor hearts. Compared to donors, only MYBPC3mut samples display a significantly diminished SRX, characterised by a decrease in both the number of myosin heads in the SRX and the lifetime of ATP turnover. These changes were not observed in HCMsmn samples. There was a positive correlation (p < 0.01) between the expression of cMyBP-C and the proportion of myosin heads in the SRX state, suggesting cMyBP-C modulates and maintains the SRX. Phosphorylation of the myosin regulatory light chain in MYBPC3mut samples was significantly decreased compared to the other groups, suggesting a potential mechanism to compensate for the diminished SRX. We conclude that by altering both contractility and sarcomeric energy requirements, a reduced SRX may be an important disease mechanism in patients with MYBPC3 mutations. Show less

Cardiac myosin binding protein-C (cMyBP-C) is a structural and regulatory component of cardiac thick filaments. It is observed in electron micrographs as seven to nine transverse stripes in the central portion of each half of the A band. Its C-terminus binds tightly to the myosin rod and contributes to thick filament structure, while the N-terminus can bind both myosin S2 and actin, influencing their structure and function. Mutations in the MYBPC3 gene (encoding cMyBP-C) are commonly associated with hypertrophic cardiomyopathy (HCM). In cardiac cells there exists a population of myosin heads in the super-relaxed (SRX) state, which are bound to the thick filament core with a highly inhibited ATPase activity. This report examines the role cMyBP-C plays in regulating the population of the SRX state of cardiac myosin by using an assay that measures single ATP turnover of myosin. We report a significant decrease in the proportion of myosin heads in the SRX state in homozygous cMyBP-C knockout mice, however heterozygous cMyBP-C knockout mice do not significantly differ from the wild type. A smaller, non-significant decrease is observed when thoracic aortic constriction is used to induce cardiac hypertrophy in mutation negative mice. These results support the proposal that cMyBP-C stabilises the thick filament and that the loss of cMyBP-C results in an untethering of myosin heads. This results in an increased myosin ATP turnover, further consolidating the relationship between thick filament structure and the myosin ATPase. Show less