Monogenic Disorders Research Articles

Neuroimaging to Genotype: Delineating the Spectrum of Disorders With Deficient Myelination in the Indian Population.

Several genetic disorders are associated with either a permanent deficit or a delay in central nervous system myelination. We investigated 24 unrelated families (25 individuals) with deficient myelination after clinical and radiological evaluation. A combinatorial approach of targeting and/or genomic testing was employed. Molecular diagnosis was achieved in 22 out of 24 families (92%). Four families (4/9, 44%) were diagnosed with targeted testing and 18 families (18/23, 78%) were diagnosed using broad genomic testing. Overall, 14 monogenic disorders were identified. Twenty disease-causing variants were identified in 14 genes including PLP1, GJC2, POLR1C, TUBB4A, UFM1, NKX6-2, DEGS1, RNASEH2C, HEXA, ATP7A, SETBP1, GRIN2B, OCLN, and ZBTB18. Among these, nine (45%) variants are novel. Fourteen families (82%, 14/17) were diagnosed using proband-only exome sequencing (ES) complemented with deep phenotyping, thus highlighting the utility of singleton ES as a valuable diagnostic tool for identifying these disorders in resource-limited settings.

Lipoprotein(a) and cardiovascular prognosis of familial dyslipidemias: data from a 10-year follow-up study

Abstract Background Familial dyslipidemias, such as heterozygous familial hypercholesterolemia (FH) and familial combined hyperlipidemia (FCH) are associated with premature cardiovascular (CV) disease. On the other hand, increased lipoprotein(a) [Lp(a)] is considered as the most prevalent monogenic lipid disorder in the general population. Purpose This study aimed to longitudinally follow up two specific populations with familial dyslipidemias associated with increased CV risk, namely FH and FCH, and compare them with reference to their CV prognosis, investigating in parallel the effect of Lp(a) levels. Methods 433 patients with FH (34% males, mean age 44.2±12.8 years) and 476 patients with FCH (57% males, mean age 49.0±11.1 years) from the outpatient lipid clinic of our hospital, without history of CV disease, who fulfilled the FH and FCH criteria, respectively, participated in the study. Participants were evaluated for a mean follow-up period of 9.6±7.6 years, with at least one annual visit. Venous blood samples were obtained at baseline in all patients for the determination of lipid profile and levels of Lp(a). All subjects were on lipid-lowering medication during the follow-up period. The endpoint of our study was the composite of major CV events (coronary artery disease events and stroke). Results The incidence of the composite endpoint of major CV events during the follow-up period in the total population was 6.5%, while it was greater in patients with FH compared to patients with FCH (8.1% vs 5.5%, p=0.03). Regarding CV risk factors, FCH compared to FH patients had greater prevalence of baseline hypertension (36% vs 9.7%, p<0.001) and diabetes (11% vs 2%, p<0.001), whereas FH patients had greater Lp(a) levels (37.4±40.3 vs 29.7±34.6 mg/dl, p<0.01). Multiple Cox regression analysis revealed that FH patients had greater CV risk compared to FCH patients (HR 2.17, 95% CI 1.10-4.26, p=0.02). Moreover, in FH patients, increased baseline Lp(a) levels (≥30mg/dl) were an independent predictor of major adverse CV events (HR 2.37 95% CI 1.41-4.90, p=0.02), whereas in FCH patients increased Lp(a) was not an independent predictor. In FCH patients the presence of diabetes at baseline was a strong independent prognosticator of adverse CV events (HR 3.56 95% CI 1.19-11.33, p=0.03), after adjustment for confounding factors. Conclusions FH patients have greater CV risk compared to FCH patients. In FH patients, the presence of increased Lp(a) doubles the CV risk, beyond low density lipoprotein cholesterol levels. On the other hand, in FCH patients the presence of diabetes triples the CV risk, whereas Lp(a) does not convey an independent prognostic value.

Management of children with heterozygous familial hypercholesterolemia worldwide: a meta-analysis

Abstract Background HeFH is one of the most frequent monogenic disorders in the world, leading to premature ASCVD. Purpose The aim of this meta-analysis was to evaluate the efficacy and safety of lipid lowering therapy (LLT) and achievement of LDL-C goal in heFH children. Methods The main endpoint was efficacy of goal achievement for LDL-C and other lipid parameters: total cholesterol [TC], triglycerides [TG], high density lipoprotein cholesterol [HDL-C], apolipoprotein B [apo B] and lipoprotein(a) [Lp(a)]), and the LLT safety (adverse events [AEs], including endocrine function, and growth indices). The secondary endpoint was an effect of LLT on attainment of LDL-C goal treatment (<3.5 mmol/L/130 mg/dL). Results A total of 41 studies with 4667 pediatric patients at mean age 12.08±2.4 years were included. At median follow-up of 18.8 months, the group on LLT had significantly higher mean reductions of TC, LDL-C, TG, and increased HDL-C compared to control (-1.75 [-67,7 mg/dl], -1.84 [-71.2 mg/dl], -0.11 [-9.74 mg/dl], 0.08 mmol/L [3.1 mg/dl], respectively, p<0.001 for all). In the subgroup analysis according to different types of LLT we observed a significantly higher mean reduction of LDL-C by statin combined with ezetimibe treatment, followed by PCSK9 inhibitors, statins in monotherapy, and monotherapy with ezetimibe (-2.48 [-95.9 mg/dl], -2.16 [-83.5 mg/dl], -2.03 [-78.5 mg/dl], and -1.50 mmol/L [-58 mg/dl], respectively, test for overall effect: p<0.001). The pooled LDL-C was reduced by 33.44% (-2.14 mmol/L [-82.8 mg/dl], p<0.001) and failed to reach the goal treatment (<3.5 mmol/L) by 12.6% (95%CI, 12.4 – 12.9%). 38.7% of children achieved the LDL-C goal, 23.9% fell short by up to 10%, 10.7% experienced moderate failure (were over the LDL-C target between >10-20%), and 26.7% failed by more than 20% to reach the LDL-C target. When comparing different regions, only Sweden and Greece achieved the LDL-C goal <3.5 mmol/L in the follow-up, followed by the Netherlands, Norway, Poland, USA, UK, France, Spain, Belgium, and Austria (with the following additional required LDL-C reduction to be on the goal: 2.2%, 3.4%, 3.5%, 8.9%, 10.2%, 11.2%, 11.2%, 15%, 19.4%, respectively). For other investigated countries over 20% mean LDL-C reduction was required. All parameters related to endocrine function and demographic indices were unaffected by LLT therapy (p>0.05). The adverse events were not reported significantly higher when compared to the control and the prevalence of therapy discontinuation was only 0.8%. Conclusions Despite the efficacy of LLT in children with HeFH and the low occurrence of discontinuation-related adverse events, achieving LDL-C treatment goals was relatively rare, with large differences between the investigated countries. These results underscore the importance of considering early combination therapy of statins and ezetimibe, and PCSK9 inhibitors (if available) to attain LDL-C goals effectively.Lipoproteins reduction with LLT.Goal achievement and therapy safety.

Advancing Precision Nutrition in Endometriosis Care: The Role of Nutrigenomics and Nutrigenetics

Endometriosis is a gynecological disorder that affects 10-15% of women of reproductive age. It is characterized as a chronic, inflammatory, and hormone-dependent disease in which the endometrial tissue is present on the external uterine lining, resulting in infertility and pelvic pain. Some research studies stated that about 97% of human diseases are monogenic diseases associated with genes. Thus, modifying dietary intake (personalized diet) can potentially prevent monogenic diseases. Nutrigenomics and nutrigenetics have garnered substantial interest among researchers as potential avenues for managing chronic conditions like diabetes, cancer, obesity, and cardiovascular disorders. Nutrigenomics ascertains the effects of food and ingested nutrients on gene expression and regulation, tailoring nutritional needs to an individual’s genetic makeup, thereby facilitating personalized diets. On the other hand, nutrigenetics investigates how an individual’s genetic composition influences their response to dietary elements. Both fields could be beneficial in modifying various disease conditions. Furthermore, it explores the effects of precision nutrition, direct-to-consumer genetic testing, and the role of artificial intelligence in the nutrigenetics and nutrigenomics approach to managing endometriosis. This review aims to provide a comprehensive overview of potential treatment modalities for endometriosis through the lenses of nutrigenomics and nutrigenetics. It highlights the interplay between dietary interventions and gene expression, elucidating how personalized approaches could potentially modify the course of endometriosis.

Uncovering ASO-Targetable Deep Intronic AIRE Variants: Insights and Therapeutic Implications.

High-throughput DNA sequencing has accelerated the discovery of disease-causing genetic variants, yet only in 10-40% of cases yield a genetic diagnosis. Increased implementation of genome sequencing has enabled a deeper exploration of the noncoding genome and recognition of noncoding variants as major contributors to disease. In a recent study, we identified a deep intronic variant in the AutoImmune REgulator (AIRE) gene (c.1504-818 G>A) as the cause of autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED), a life-threatening monogenic autoimmune disorder most often caused by biallelic AIRE defects. This deep intronic variant disrupts normal splicing AIRE , causing pseudoexon inclusion and altered protein function. By developing an antisense oligonucleotide (ASO) targeting the pseudoexon sequence, we restored normal AIRE transcript in vitro, thereby revealing a potential genotype-specific candidate treatment. Our study illustrates key aspects of intronic variant detection, validation, and candidate ASO development. Herein, we briefly highlight the growing potential of ASO-based therapies for deep intronic variants, addressing the unmet need of personalized, genotype-specific therapies in diseases lacking curative options.

Accurate prenatal diagnosis of facioscapulohumeral muscular dystrophy 1 using nanopore sequencing

BackgroundFacioscapulohumeral muscular dystrophy 1 (FSHD1) is an autosomal dominant muscular disorder mainly caused by the contraction and hypomethylation of the D4Z4 repeat array in chromosome 4q35. Prenatal diagnosis of FSHD1...

Clinical utility of expanded carrier screening in the preconception and prenatal population: A Chinese cohort study

ObjectivesTo evaluate the clinical utility of expanded carrier screening (ECS) in Chinese preconception and prenatal populations, focusing on carrier frequency and the impact on at-risk couples (ARCs). MethodsData from 6,298 Chinese individuals from 4,420 families who underwent a 149-gene ECS panel at a single center were analyzed. The prevalence of positive carriers and ARCs was determined, with follow-up on reproductive decisions and pregnancy outcomes for ARCs. ResultsOf the individuals screened, 2,673 (42.4 %) were carriers of at least one pathogenic or likely pathogenic variant, and 98 (2.22 %) ARCs were identified. GJB2-related deafness and Duchenne muscular dystrophy were the most common autosomal recessive (AR) and X-linked disorders. Screening the top 11 (gene carrier rate [GCR] ≥ 1/100), 22 (GCR ≥ 1/200), and 41 (GCR ≥ 1/331) AR genes could identify 53.5 %, 67.9 %, and 81.3 % of variants, respectively. The corresponding ratios for identified ARCs were 90.4 %, 94.0 %, and 100 %. Follow-up data from 80 ARCs indicated that 75.0 % (60/80) took significant action based on the ECS results. Additionally, four families (3.5 %, 4/115) were identified at risk for a second disease unrelated to their initial family monogenic history. ConclusionsThis study, representing the largest cohort of a moderate-sized ECS panel test in the Chinese population, demonstrates the clinical utility of ECS in both healthy individuals and those with a family history of monogenic disorders. The data obtained provide valuable insights for developing a Chinese-specific ECS panel. Tailored approaches are critical for wider adoption and successful routine application of ECS.

Clinical and Genetic characteristics of patients with Peripheral Retinal Fleck in Koreans.

To describe the clinical and genetic features of Korean patients with peripheral retinal flecks unrelated to aging. A retrospective analysis was conducted on the clinical characteristics of patients with symmetric peripheral retinal flecks. Age-related deposits such as reticular pseudodrusen were excluded, as well as secondary deposits related to intraocular inflammation, tumor, and drug toxicity. Multimodal imaging, electrophysiological examinations, and genetic testing were analyzed. A total of 10 patients (2 males and 8 females) with bilateral peripheral flecks were enrolled in this study. A mean age at diagnosis was 30.5±19.6 years (4-59 years). Within the 10 patients, 6 were genetically confirmed with monogenic retinal disorders. Biallelic pathogenic variants in RDH5 were found in 5 patients, and 1 patient was diagnosed with retinopathy related to Alport syndrome due to a pathogenic variant in COL4A5. Although not genetically confirmed, one case associated with nanophthalmos and another case showing chorioretinal mottling in a carrier of ocular albinism have been identified. In one patient, genetic testing also revealed unknown causes. The mean logMAR initial visual acuity was 0.12±0.18 and 0.07±0.18 in right and left eyes, respectively. Night blindness was reported by 4 patients (40%), with 3 showing decreased or delayed rod response in electroretinogram, particularly those with RDH5 mutations. Differences in the deposit layers and the patterns of flecks were observed on multimodal imaging. In the study population, we observed various causes and clinical differences in the retinal fleck patterns among Koreans, including RDH5-related fundus albipunctatus and Alport syndrome. Despite reports of night blindness symptoms in some cases, all patients demonstrated satisfactory corrected visual acuity.

Genetics in nephrology - any news?

While genetic kidney diseases were long regarded as a rare cause of kidney failure, it has been shown in recent years that they account for a relevant proportion of cases. In cohorts of kidney transplant recipients, a monogenic cause is found in up to 30% of cases. Identifying the genetic cause of kidney disease has become much easier thanks to technological advances in DNA sequencing. The focus has now shifted to understanding the significance of the findings and identifying diagnostic gaps. It is still not possible to clarify all CKD cases of unclear aetiology. Besides very effective generic treatments for monogenic kidney disease (e.g., ACE-inhibitor use in Alport Syndrome), increasing knowledge of the pathophysiology of genetic kidney diseases has led to a growing number of targeted therapies. These include the treatment of ADPKD with Tolvaptan, which has now been in use for 10 years. Recently, exciting, and completely new approaches have been added, such as the first siRNA therapies in nephrology for primary hyperoxaluria type 1, the targeted treatment of hyperphagia in Bardet-Biedl syndrome, the therapy of APOL1-associated kidney disease or the use of the HIF-2 antagonist Belzutifan for renal cell carcinoma associated with Von-Hippel-Lindau syndrome. The new possibilities in the treatment of patients with genetic kidney diseases have also clearly revealed deficits in current patient care. Centers of excellence with extensive experience in this area therefore play an important role in improving care. This also applies to the further training of colleagues in the field. In Germany, the National Action Alliance for People with Rare Diseases (NAMSE) and the nationwide establishment of - to date - 36 centers for rare diseases play an important role in this regard.

Global cellular proteo-lipidomic profiling of diverse lysosomal storage disease mutants using nMOST.

Lysosomal storage diseases (LSDs) comprise ~50 monogenic disorders marked by the buildup of cellular material in lysosomes, yet systematic global molecular phenotyping of proteins and lipids is lacking. We present a nanoflow-based multi-omic single-shot technology (nMOST) workflow that quantifies HeLa cell proteomes and lipidomes from over two dozen LSD mutants. Global cross-correlation analysis between lipids and proteins identified autophagy defects, notably the accumulation of ferritinophagy substrates and receptors, especially in NPC1-/- and NPC2-/- mutants, where lysosomes accumulate cholesterol. Autophagic and endocytic cargo delivery failures correlated with elevated lyso-phosphatidylcholine species and multi-lamellar structures visualized by cryo-electron tomography. Loss of mitochondrial cristae, MICOS-complex components, and OXPHOS components rich in iron-sulfur cluster proteins in NPC2-/- cells was largely alleviated when iron was provided through the transferrin system. This study reveals how lysosomal dysfunction affects mitochondrial homeostasis and underscores nMOST as a valuable discovery tool for identifying molecular phenotypes across LSDs.

An update on autophagy disorders.

Macroautophagy is a highly conserved cellular pathway for the degradation and recycling of defective cargo including proteins, organelles, and macromolecular complexes. As autophagy is particularly relevant for cellular homeostasis in post-mitotic tissues, congenital disorders of autophagy, due to monogenic defects in key autophagy genes, share a common "clinical signature" including neurodevelopmental, neurodegenerative, and neuromuscular features, as well as variable abnormalities of the eyes, skin, heart, bones, immune cells, and other organ systems, depending on the expression pattern and the specific function of the defective proteins. Since the clinical and genetic resolution of EPG5-related Vici syndrome, the paradigmatic congenital disorder of autophagy, the widespread use of massively parallel sequencing has resulted in the identification of a growing number of autophagy-associated disease genes, encoding members of the core autophagy machinery as well as related proteins. Recently identified monogenic disorders linking selective autophagy, vesicular trafficking, and other pathways have further expanded the molecular and phenotypical spectrum of congenital disorders of autophagy as a clinical disease spectrum. Moreover, significant advances in basic research have enhanced the understanding of the underlying pathophysiology as a basis for therapy development. Here, we review (i) autophagy in the context of other intracellular trafficking pathways; (ii) the main congenital disorders of autophagy and their typical clinico-pathological signatures; and (iii) the recommended primary health surveillance in monogenic disorders of autophagy based on available evidence. We further discuss recently identified molecular mechanisms that inform the current understanding of autophagy in health and disease, as well as perspectives on future therapeutic approaches.

The Need for Speed; Investigating Channelopathy-Associated Epilepsy Using High Throughput Electrophysiological Approaches

Pathogenic variants in genes encoding ion channels are frequently discovered in monogenic disorders associated with epilepsy and neurodevelopmental disorders. This review covers advances in the use of automated patch clamp recording for determining the functional consequences of epilepsy-associated ion channel variants and the use of induced pluripotent stem cell (iPSC) derived neurons for in-depth investigations of the physiological consequences of such variants. The combination of these advanced technologies was a focus of the recently completed NINDS-funded Channelopathy-associated Epilepsy Research Center without Walls.

Recurrent calcium oxalate calculi: the culprit in disguise.

Congenital sucrase isomaltase deficiency (CSID) is a rare autosomal recessive monogenic disorder of small intestinal malabsorption and manifests typically in early childhood with chronic osmotic diarrhoea. Though there have been case reports in adults presenting with hypercalcemia and renal calculi in CSID, this is quite rare in children. We hereby report a 6-year-old boy who presented with recurrent episodes of calcium oxalate calculi without any gastrointestinal symptoms and was confirmed as having sucrase isomaltase deficiency by genetic analysis.

Dysregulation of epigenetic modifications in inborn errors of immunity.

Inborn errors of immunity (IEIs) are a group of typically monogenic disorders characterized by dysfunction in the immune system. Individuals with these disorders experience increased susceptibility to infections, autoimmunity and malignancies due to abnormal immune responses. Epigenetic modifications, including DNA methylation, histone modifications and chromatin remodeling, have been well explored in the regulation of immune cell development and effector function. Aberrant epigenetic modifications can disrupt gene expression profiles crucial for immune responses, resulting in impaired immune cell differentiation and function. Dysregulation of these processes caused by mutations in genes involving in epigenetic modifications has been associated with various IEIs. In this review article, we focus on IEIs that are caused by mutations in 13 genes involved in the regulation of DNA methylation, histone modification and chromatin remodeling.

Cell-Type Resolved Protein Atlas of Brain Lysosomes Identifies SLC45A1-Associated Disease as a Lysosomal Disorder.

Mutations in lysosomal genes cause neurodegeneration and neurological lysosomal storage disorders (LSDs). Despite their essential role in brain homeostasis, the cell-type-specific composition and function of lysosomes remain poorly understood. Here, we report a quantitative protein atlas of the lysosome from mouse neurons, astrocytes, oligodendrocytes, and microglia. We identify dozens of novel lysosomal proteins and reveal the diversity of the lysosomal composition across brain cell types. Notably, we discovered SLC45A1, mutations in which cause a monogenic neurological disease, as a neuron-specific lysosomal protein. Loss of SLC45A1 causes lysosomal dysfunction in vitro and in vivo. Mechanistically, SLC45A1 plays a dual role in lysosomal sugar transport and stabilization of V1 subunits of the V-ATPase. SLC45A1 deficiency depletes the V1 subunits, elevates lysosomal pH, and disrupts iron homeostasis causing mitochondrial dysfunction. Altogether, our work redefines SLC45A1-associated disease as a LSD and establishes a comprehensive map to study lysosome biology at cell-type resolution in the brain and its implications for neurodegeneration.

The Clinical Genome Resource (ClinGen): Advancing genomic knowledge through global curation.

The Clinical Genome Resource (ClinGen) is a National Institutes of Health-funded program founded 10 years ago that defines the clinical relevance of genes and variants for medical and research use. ClinGen working groups develop standards for data sharing and curating genomic knowledge. Expert panels, with >2500 active members from 67 countries, curate the validity of monogenic disease relationships, pathogenicity of genetic variation, dosage sensitivity of genes, and actionability of gene-disease interventions using ClinGen standards, infrastructure, and curation interfaces. Results are available on clinicalgenome.org and classified variants are also submitted to ClinVar, a publicly available database hosted by the National Institutes of Health. As of January 2024, over 2700 genes have been curated (2420 gene-disease relationships for validity, 1557 genes for dosage sensitivity, and 447 gene-condition pairs for actionability), and 5161 unique variants have been classified for pathogenicity. New efforts are underway in somatic cancer, complex disease and pharmacogenomics, and a systematic approach to addressing justice, equity, diversity, and inclusion. ClinGen's knowledge can be used to build evidence-based genetic testing panels, interpret copy-number variation, resolve discrepancies in variant classification, guide disclosure of genomic findings to patients, and assess new predictive algorithms. To get involved in ClinGen activities go to https://www.clinicalgenome.org/start.

Autism Spectrum Disorder Symptom Profiles in Fragile X Syndrome, Angelman Syndrome, Tuberous Sclerosis Complex and Neurofibromatosis Type 1.

Studying Autism Spectrum Disorder (ASD) heterogeneity in biologically homogeneous samples may increase our knowledge of ASD etiology. Fragile X syndrome (FXS), Angelman syndrome (AS), Tuberous Sclerosis Complex (TSC), and Neurofibromatosis type 1 (NF1) are monogenic disorders with high a prevalence of ASD symptomatology. This study aimed to identify ASD symptom profiles in a large group of children and adolescents (0;9-28 years) with FXS, AS, TSC, and NF1. Data on ASD symptomatology (Autism Diagnostic Observation Scale (ADOS-2) & Social Responsiveness Scale (SRS-2)) were collected from children and adolescents with FXS (n = 54), AS (n = 93), TSC (n = 112), and NF1 (n = 278). To identify groups of individuals with similar ASD profiles, we performed two latent profile analyses. We identified a four-profile model based on the ADOS-2, with a (1) 'Non-spectrum symptom profile', (2) 'Social Affect symptom profile', (3)'Restricted/Repetitive Behaviors symptom profile', and (4)'ASD symptom profile'. We also identified a four-profile model based on the SRS, with a (1)'Non-clinical symptom profile', (2)'Mild symptom profile', (3)'Moderate symptom profile', and (4)'Severe symptom profile'. Although each syndrome group exhibited varying degrees of severity, they also displayed heterogeneity in the profiles in which they were classified. We found distinct ASD symptom profiles in a population consisting of children and adolescents with FXS, AS, TSC, and NF1. Our study highlights the importance of a personalized approach to the identification and management of ASD symptoms in rare genetic syndromes. Future studies should aim to include more domains of functioning and investigate the stability of latent profiles over time.

CRISPR/Cas system in human genetic diseases

The Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) system is an adaptive immune system derived from bacteria which is designed to recognize and cleave invading DNA, such as viruses and plasmids. The advent of this innovative gene-editing technology has emerged as influential force in the category of medicine, delivering unprecedented precision in targeting and modifying genetic material. This review explores the potential and challenges of CRISPR in the context of human diseases. Specific applications in diseases affecting hemoglobin, muscle, the eye, and the liver are examined, demonstrating the versatility of CRISPR in addressing both monogenic and complex diseases. The use of CRISPR for gene therapy in conditions like sickle cell disease, Duchenne muscular dystrophy, retinal degeneration, and liver disorders is discussed, showcasing early clinical trials and preclinical studies that underscore the promise of CRISPR in medicine. Finally, it is expected that CRISPR will be able to play a greater role in human health and bring more precise and personalized treatment plans to patients.

Somatic mutations in autoinflammatory and autoimmune disease.

Somatic mutations (also known as acquired mutations) are emerging as common, age-related processes that occur in all cells throughout the body. Somatic mutations are canonically linked to malignant processes but over the past decade have been increasingly causally connected to benign diseases including rheumatic conditions. Here we outline the contribution of somatic mutations to complex and monogenic immunological diseases with a detailed review of unique aspects associated with such causes. Somatic mutations can cause early- or late-onset rheumatic monogenic diseases but also contribute to the pathogenesis of complex inflammatory and immune-mediated diseases, affect disease progression and define new clinical subtypes. Although even variants with a low variant allele fraction can be pathogenic, clonal dynamics could lead to changes over time in the proportion of mutant cells, with possible phenotypic consequences for the individual. Thus, somatic mutagenesis and clonal expansion have relevant implications in genetic testing and counselling. On the basis of both increased recognition of somatic diseases in clinical practice and improved technical and bioinformatic processes, we hypothesize that there will be an ever-expanding list of somatic mutations in various genes leading to inflammatory conditions, particularly in late-onset disease.

Analysis of low-density lipoprotein receptor gene mutations in a family with familial hypercholesterolemia.

Familial hypercholesterolemia (FH) is a common monogenic autosomal dominant disorder, primarily mainly caused by pathogenic mutations in the low-density lipoprotein receptor (LDLR) gene. Through phenotypic-genetic linkage analysis, two LDLR pathogenic mutations were identified in FH families: c.G1027A (p.Gly343Ser) and c.G1879A (p.Ala627Thr). Whole exome sequencing was conducted on the proband with familial hypercholesterolemia to identify the target gene and screen for potential pathogenic mutations. The suspicious responsible mutation sites in 14 family members were analyzed using Sanger sequencing to assess genotype-phenotype correlations. Mutant and wild type plasmids were constructed and transfected into HEK293T cells to evaluate LDLR mRNA and protein expression. In parallel, bioinformatics tools were employed to predict structural and functional changes in the mutant LDLR. Immunofluorescence analysis revealed no significant difference in the intracellular localization of the p.Gly343Ser mutation, whereas protein expression of the p.Ala627Thr mutation was decreased and predominantly localized in the cytoplasm. Western blotting has showed that protein expression levels of the mutant variants were markedly declined in both cell lysates and supernatants. Enzyme linked immunosorbent assay has demonstrated that LDLR protein levels in the supernatant of cell culture medium was not significant different from those of the wild-type group. However, LDLR protein levels in the cell lysate of both the Gly343Ser and Ala627Thr variants groups were significantly lower than those in the wild-type group. Bioinformatic predictions further suggested that these mutations may affect post-translational modifications of the protein, providing additional insight into the mechanisms underlying the observed reduction in protein expression. In this study, we identified two heterozygous pathogenic variants in the LDLR gene, c.G1027A (p.Gly343Ser) and c.G1879A (p.Ala627Thr), in a family with familial hypercholesterolemia. We also conducted preliminary investigations into the mechanisms by which these mutations contribute to disease pathology.