Search Results (1,263)

Moyamoya disease (MMD) is primarily associated with genetic variants in RNF213. RNF213 p.R4810K (c.14429G>A, p.Arg4810Lys) is a founder variant predominantly found in East Asian populations and is strongly associated with MMD, a rare cerebrovascular condition characterized by progressive stenosis of intracranial arteries and the development of abnormal collateral networks. Recent evidence suggests that RNF213 variants are also enriched in non-moyamoya intracranial arteriopathies, such as large-artery atherosclerotic stroke and intracranial arterial stenosis/occlusion (ICASO), particularly in east Asian individuals with early-onset or cryptogenic stroke. This expanded phenotypic spectrum, termed RNF213-related vasculopathy (RRV), represents a distinct pathogenic entity that may involve unique pathogenic processes separate from traditional atherosclerosis. In this review, we synthesize current genetic, clinical, radiological, and experimental findings that delineate the unique features of RRV. Patients with RRV typically exhibit a lower burden of traditional vascular risk factors, negative vascular remodeling in the absence of atheromatous plaques, and an increased propensity for disease progression. RNF213 variants may compromise vascular resilience by impairing adaptive responses to hemodynamic stress. Furthermore, emerging cellular and animal model data indicate that RNF213 influences angiogenesis, lipid metabolism, and stress responses, offering mechanistic insights into its role in maintaining vascular integrity. Recognizing RRV as a distinct clinical entity has important implications for diagnosis, risk stratification, and the development of genome-informed therapeutic strategies. Full article

Background/Objectives: Glycogen storage disease type II, also known as Pompe disease (PD), is a rare autosomal recessive genetic disorder triggered by a deficiency in lysosomal acid α-glucosidase (GAA). Recently, we discovered two deleterious missense variants of the GAA gene, c.1799G>A (p.Arg600His) (a pathogenic mutation) and c.55G>A (p.Val19Met), in a domestic short-haired cat with PD. This study aimed to design genotyping assays for these two variants and ascertain their allele frequencies in Japanese cat populations. Methods: We developed fluorescent probe-based real-time polymerase chain reaction assays to genotype the c.1799G>A and c.55G>A variants. A total of 738 cats, comprising 99 purebred cats from 20 breeds and 540 mixed-breed cats, were screened using these assays. Results: Genotyping assays clearly differentiated all known genotypes of the two variants. None of the 738 cats tested carried the c.1799G>A variant. However, we identified cats with c.55G/A and c.55A/A genotypes in the purebred (A allele frequency: 0.081) and mixed-breed cats (0.473). A significant difference (p < 0.001) was observed in the A allele frequency between the two groups. Conclusions: The c.1799G>A mutation appears rare in cat populations, suggesting it may be confined to specific pedigree Japanese mixed-breed cats. The c.55G>A variant was detected in purebred and mixed-breed cats, suggesting that it may not be directly linked to feline PD. However, additional studies are required to elucidate the precise relationship between this variant and cardiac function. Genotyping assays will serve as valuable tools for diagnosing and genotyping feline PD. Full article

Conventional melanoma is exceedingly rare in the pediatric population, particularly among prepubescent children, and its diagnosis and management necessitate a multidisciplinary approach. The objective of this present report is to delineate the diagnostic pathway and therapeutic management of a 4-year-old girl with conventional melanoma, with particular focus on the molecular context. A pigmented lesion located on the auricle was surgically excised, and subsequent histopathological and immunohistochemical analyses confirmed the diagnosis of malignant melanoma (pT3b). Radiologic investigations revealed no evidence of metastatic disease, and comprehensive genetic testing utilizing next-generation sequencing (NGS) identified no pathogenic variants in the germline genes examined, nor in the BRAF, NRAS, KRAS, and TP53 genes within the excised lesion. The patient remains in good general health. This case report adds to the limited body of literature on melanoma in pediatric patients and underscores the importance of thorough diagnostic evaluation in this age group. Full article

Background: Endometriosis is a chronic inflammatory condition affecting 10–15% of women of reproductive age. Genome-wide association studies (GWASs) have accounted for only a fraction of its high heritability, indicating the need for alternative approaches to identify rare genetic variants contributing to its etiology. To this end, we performed whole-exome sequencing (WES) in a multi-affected family. Methods: A multigenerational family was studied, comprising three sisters, their mother, grandmother, and a daughter, all diagnosed with endometriosis. WES was conducted on the three sisters and their mother. We used the enGenome-Evai and Varelect software to perform our analysis, which mainly focused on rare, missense, frameshift, and stop variants. Results: Bioinformatic analysis identified 36 co-segregating rare variants. Six missense variants in genes associated with cancer growth were prioritized. The top candidates were c.3319G>A (p.Gly1107Arg) in the LAMB4 gene and c.1414G>A (p.Gly472Arg) in the EGFL6 gene. Variants in NAV3, ADAMTS18, SLIT1, and MLH1 may also contribute to disease onset through a synergistic and additive model. Conclusions: We identified novel candidate genes for endometriosis in a multigenerational affected family, supporting a polygenic model of the disease. Our study is an exploratory family-based WES study, and replication and functional studies are warranted to confirm these preliminary findings. Full article

The management of acute lymphoblastic leukemia (ALL), the most common pediatric malignancy, critically relies on thiopurine therapy, such as 6-mercaptopurine (6-MP), during the maintenance phase. However, significant inter-individual response variety and high risk of myelosuppression often disrupt therapy efficacy. Pharmacogenetics offer crucial strategies to personalized therapy. While thiopurine methyltransferase (TPMT) was initially the primary focus, the discovery of nudix hydrolase 15 (NUDT15) appears as a more comprehensive determinant of thiopurine intolerance. This review aims to consolidate and critically evaluate the advancement achieved in unraveling the biological mechanism and clinical significance of NUDT15 pharmacogenetics in thiopurine therapy. Foundational studies showed the vital role of NUDT15 in the detoxification of active thiopurines, with common genetic variants (for instance, p. Arg139Cys) significantly disrupting its activity, leading to the accumulation of toxic metabolites. Observational studies consistently associated NUDT15 variants with severe myelosuppression, notably in Asian populations. Recent randomized controlled trials (RCTs) confirmed that NUDT15 genotype-guided dosing effectively reduces thiopurine-induced toxicity without interfering with the therapeutic outcome. Despite these advancements, challenges remain present, including the incomplete characterization of rare variants, limited data in the diverse Asian populations, and the need for standardized integration with metabolite monitoring. In conclusion, NUDT15 pharmacogenetics is essential for improving patient safety and thiopurine dosage optimization in the treatment of ALL. For thiopurine tailored medicine to be widely and fairly implemented, future research should focus on increasing genetic data across different populations, improving the dose adjustment algorithm, and harmonizing therapeutic guidelines. Full article

Nephrotic syndrome (NS) is characterized by proteinuria, hypoalbuminemia, edema, and hyperlipidemia. Apart from the traditional causes of NS, such as minimal change disease, focal segmental glomerulosclerosis, diabetes, infections, malignancies, autoimmune conditions, and nephrotoxic agents, there are also rare causes of NS, whose knowledge is of the utmost importance. The aim of this article was to highlight the less well-known causes that have a significant impact on diagnosis and treatment. Genetic syndromes such as Schimke immuno-osseous dysplasia, familial lecithin-cholesterol acyltransferase deficiency with two clinical variants (fish-eye Disease and the p.Leu364Pro mutation), lead to NS through mechanisms involving podocyte and lipid metabolism dysfunction. Congenital disorders of glycosylation and Nail–Patella Syndrome emphasize the role of deranged protein processing and transcriptional regulation in glomerular injury. The link of NS with type 1 diabetes, though rare, suggests an etiology on the basis of common HLA loci and immune dysregulation. Histopathological analysis, particularly electron microscopy, shows mainly podocyte damage, mesangial sclerosis, and alteration of the basement membrane, which aids in differentiating rare forms. Prompt recognition of these novel etiologies by genetic analysis, renal biopsy, and an interdisciplinary panel is essential to avoid delays in diagnosis and tailored treatment. Full article

SARS-CoV-2 undergoes frequent mutations that drive viral evolution and genomic diversity, influencing transmissibility, immune escape, and disease severity. In this study, we performed whole-genome sequencing on SARS-CoV-2 isolates from patients in New York City and identified several globally rare mutations across multiple viral lineages. The isolates analyzed for rare mutations belonged to three lineages: B.1.1.7 (Alpha), B.1.526 (Iota), and B.1.623. We identified 16 rare mutations (global incidence <1000) in non-structural protein genes, including nsp2, nsp3, nsp4, nsp6, nsp8, nsp13, nsp14, ORF7a, and ORF8. Three of these mutations—located in nsp2, nsp13, and ORF8—have been reported in fewer than 100 individuals worldwide. We also detected five rare mutations in structural proteins (S, M, and N), including two—one in M and one in N—previously reported in fewer than 100 cases globally. We present clinical profiles of three patients, each infected with genetically distinct viral isolates from the three lineages studied. Furthermore, we illustrate a local transmission chain inferred from unique mutation patterns identified in the Omicron genome. These findings underscore the importance of whole-genome sequencing for detecting rare mutations, tracking community spread, and identifying emerging variants with clinical and public health significance. Full article

Background/Objectives: Hutchinson–Gilford progeria syndrome (HGPS) is a rare and fatal genetic disease caused by a silent mutation in the LMNA gene, leading to the production of progerin, a defective prelamin A variant. Progerin accumulation disrupts nuclear integrity, alters chromatin organization, and drives systemic cellular dysfunction. While autophagy and inflammation are key dysregulated pathways in HGPS, the role of microRNAs (miRNAs) in these processes remains poorly understood. Methods: We performed an extensive literature review to identify miRNAs involved in autophagy and inflammation. Through stem-loop RT-qPCR in aging HGPS and control fibroblast strains, we identified significant miRNAs and focused on the most prominent one, miR-181a-5p, for in-depth analysis. We validated our in vitro findings with miRNA expression studies in skin biopsies from an HGPS mouse model and conducted functional assays in human fibroblasts, including immunofluorescence staining, β-Galactosidase assay, qPCR, and Western blot analysis. Transfection studies were performed using an miR-181a-5p mimic and its inhibitor. Results: We identified miR-181a-5p as a critical regulator of premature senescence in HGPS. miR-181a-5p was significantly upregulated in HGPS fibroblasts and an HGPS mouse model, correlating with Sirtuin 1 (SIRT1) suppression and induction of senescence. Additionally, we demonstrated that TGFβ1 induced miR-181a-5p expression, linking inflammation to miRNA-mediated senescence. Inhibiting miR-181a-5p restored SIRT1 levels, increased proliferation, and alleviated senescence in HGPS fibroblasts, supporting its functional relevance in disease progression. Conclusions: These findings highlight the important role of miR-181a-5p in premature aging and suggest its potential as a therapeutic target for modulating senescence in progeroid syndromes. Full article

Background: Congenital diarrhea is persistent diarrhea that manifests during the neonatal period. Mutations in DGAT1, which is crucial for triglyceride synthesis and lipid absorption in the small intestine, are causal factors for congenital diarrhea. In this study, we aimed to determine the value of tissue RNA sequencing (RNA-seq) for assisting with the clinical diagnosis of some genetic variants of uncertain significance. Methods: We clinically evaluated a patient with watery diarrhea, vomiting, severe malnutrition, and total parenteral nutrition dependence. Possible pathogenic variants were detected using whole-exome sequencing (WES). RNA-seq was utilized to explore the transcriptional alterations in DGAT1 variants identified by WES with unknown clinical significance, according to the American College of Medical Genetics guidelines. Systemic examinations, including endoscopic and histopathological examinations of the intestinal mucosa, were conducted to rule out other potential diagnoses. Results: We successfully diagnosed a patient with congenital diarrhea and protein-losing enteropathy caused by a DGAT1 mutation and reviewed the literature of 19 cases of children with DGAT defects. The missense mutation c.620A>G, p.Lys207Arg located in exon 15, and the intronic mutation c.1249-6T>G in DGAT1 were identified by WES. RNA-seq revealed two aberrant splicing events in the DGAT1 gene of the patient’s small intestinal tissue. Both variants lead to loss-of-function consequences and are classified as pathogenic variants of congenital diarrhea. Conclusions: Rare DGAT1 variants were identified as pathogenic evidence of congenital diarrhea, and the detection of tissue-specific mRNA splicing and transcriptional effects can provide auxiliary evidence. Full article

Congenital cataracts (CCs) are a leading cause of preventable childhood blindness, with genetic factors playing a crucial role in their etiology. Nance–Horan syndrome (NHS) is a rare X-linked dominant disorder associated with CCs but is often underdiagnosed due to variable expressivity, particularly in female carriers. Objective: This study aimed to explore the genetic landscape of CCs in a Swiss cohort, focusing on two novel NHS and one novel GJA8 variants and their phenotypic presentation. Methods: Whole-exome sequencing (WES) was conducted on 20 unrelated Swiss families diagnosed with CCs. Variants were analyzed for pathogenicity using genetic databases, and segregation analysis was performed. Clinical data, including cataract phenotype and associated systemic anomalies, were assessed to establish genotype–phenotype correlations. Results: Potentially pathogenic DNA sequence variants were identified in 10 families, including three novel variants, one in GJA8 (c.584T>C) and two NHS variants (c.250_252insA and c.484del). Additional previously reported variants were detected in CRYBA1, CRYGC, CRYAA, MIP, EPHA2, and MAF, reflecting genetic heterogeneity in the cohort. Notably, NHS variants displayed significant phenotypic variability, suggesting dose-dependent effects and X-chromosome inactivation in female carriers. Conclusions: NHS remains underdiagnosed due to its variable expressivity and the late manifestation of systemic features, often leading to misclassification as isolated CC. This study highlights the importance of genetic testing in unexplained CC cases to improve early detection of syndromic forms. The identification of novel NHS and GJA8 variants provides new insights into the genetic complexity of CCs, emphasizing the need for further research on genotype–phenotype correlations. Full article

Background and Clinical Significance: Multiple Endocrine Neoplasia type 1 (MEN1) is a rare autosomal dominant disorder caused by mutations in the MEN1 gene. Although primarily characterized by endocrine tumors, renal manifestations remain underreported. Case Presentation: We report a three-generation family carrying a pathogenic MEN1 mutation (c.1351-3_1359del) with a co-occurring Claudin 16 (CLDN16) variant (c.324+13C>G). Genetic testing included MLPA and whole-exome sequencing (WES), with bioinformatics analysis validating variant pathogenicity. All three patients exhibited primary hyperparathyroidism, hypercalcemia, hypercalciuria, early nephrocalcinosis, and renal hypomagnesemia. The CLDN16 variant, previously considered benign, co-segregated with hypomagnesemia and renal involvement, suggesting a potential modifying role. Conclusions: These findings support the need for comprehensive genetic screening in MEN1 patients with atypical renal presentations. Concomitant genetic variations can alter the principal phenotype. Full article

Primary ciliary dyskinesia (PCD) is a rare, genetically heterogeneous disorder that impairs mucociliary clearance and leads to progressive lung disease. This study aimed to characterize lung function decline in a genetically homogeneous cohort of Puerto Rican patients with RSPH4A-associated PCD and to develop a clinical tool to predict lung function decline and support transplant referral decisions. We conducted a retrospective chart review of patients (n = 25) with a confirmed RSPH4A [c.921+3_6delAAGT] genetic variant, collecting longitudinal spirometry data and applying linear regressions to calculate each patient’s individual FEV₁ decline. The median FEV₁ at diagnosis was 55%, with a median annual decline of −0.75% predicted. Adults exhibited significantly lower lung function compared to pediatric patients, while no difference was seen between males and females. Based on this observed decline, we developed the Predicted Capacity Decline Index (PCDx), an index that estimates the age and time until a patient reaches the 30% FEV₁ threshold, the point at which lung transplant referral is typically considered. Our findings underscore the need for early intervention and suggest that genotype-specific tools like the PCDx may enhance clinical decision-making in managing progressive lung disease in PCD. Full article

Nephrogenic diabetes insipidus (NDI) is a rare hereditary disorder characterized by renal resistance to arginine vasopressin (AVP), resulting in the kidneys’ inability to concentrate urine. Approximately 90% of NDI cases follow an X-linked inheritance pattern and are associated with pathogenic variants in the AVPR2 gene, which encodes the vasopressin receptor type 2. The remaining 10% are attributed to mutations in the AQP2 gene, which encodes aquaporin-2, and may follow either autosomal dominant or recessive inheritance patterns. We present the case of a male infant, younger than nine months of age, who was clinically diagnosed with NDI at six months. The patient presented recurrent episodes of polydipsia, polyuria, dehydration, hypernatremia, and persistently low urine osmolality. Despite adjustments in pharmacologic treatment and strict monitoring of urinary output, the clinical response remained suboptimal. Given the lack of improvement and the radiological finding of an absent posterior pituitary (neurohypophysis), the possibility of coexistent central diabetes insipidus (CDI) was raised, prompting a therapeutic trial with desmopressin. Nevertheless, in the absence of clinical improvement, desmopressin was discontinued. The patient’s management was continued with hydrochlorothiazide, ibuprofen, and a high-calorie diet restricted in sodium and protein, resulting in progressive clinical stabilization. Whole-exome sequencing identified a novel homozygous missense variant in the AQP2 gene (c.398T > A; p.Val133Glu), classified as likely pathogenic according to the American College of Medical Genetics and Genomics (ACMG) criteria: PM2 (absent from population databases), PP2 (missense variant in a gene with a low rate of benign missense variation), and PP3 (multiple lines of computational evidence supporting a deleterious effect)]. NDI is typically diagnosed during early infancy due to the early onset of symptoms and the potential for severe complications if left untreated. In this case, although initial clinical suspicion included concomitant CDI, the timely initiation of supportive management and the subsequent incorporation of molecular diagnostics facilitated a definitive diagnosis. The identification of a previously unreported homozygous variant in AQP2 contributed to diagnostic confirmation and therapeutic decision-making. The diagnosis and comprehensive management of NDI within the context of polyuria-polydipsia syndrome necessitates a multidisciplinary approach, integrating clinical evaluation with advanced molecular diagnostics. The novel AQP2 c.398T > A (p.Val133Glu) variant described herein was associated with early and severe clinical manifestations, underscoring the importance of genetic testing in atypical or treatment-refractory presentations of diabetes insipidus. Full article

Background: Cardiac involvement is common in Fabry disease (FD) and typically manifests with left ventricular hypertrophy (LVH). Patients with FD are frequently misdiagnosed, and this is mainly related to the lack of disease awareness among clinicians. The aim of this study was to determine whether providing a targeted educational intervention on FD may enhance FD diagnosis. Methods. This research was designed as a single-arm before-and-after intervention study and evaluated the impact of providing a specific training on FD to cardiologists from different Italian centers, without experience in rare diseases. In the 12-month period after the educational intervention, the rate of FD screening and diagnosis was assessed and compared with those conducted in the two years preceding the study initiation. Results: Fifteen cardiologists participated to this study, receiving a theoretical and practical training on FD. In the two previous two years, they conducted 12 FD screening (6/year), and they did not detect any cases of FD. After the training, they performed 45 FD screenings, with an eight-fold rise in the annual screening rate. The screened population (age: 61 ± 11 years, men: 82%) was mainly composed of patients with unexplained LVH (n = 43). There were four new FD diagnoses and, among of them, three had a late-onset GLA variant. After the cascade genetic screening, 11 affected relatives and 8 heterozygous carriers were also detected. Conclusions: A targeted educational intervention for cardiologists allowed the identification of four new families with FD. Enhancing FD awareness is helpful to reduce the diagnostic and therapeutic delay. Full article

Background: Charcot–Marie–Tooth disease (CMT) is a genetically and phenotypically heterogeneous hereditary neuropathy. Axonal CMT type 2 (CMT2) subtypes often exhibit overlapping clinical features, which makes molecular genetic analysis essential for accurate diagnosis and subtype differentiation. Methods: This retrospective study included five pediatric patients who presented with gait disturbance, muscle weakness, and foot deformities and were subsequently diagnosed with axonal forms of CMT. Clinical data, electrophysiological studies, neuroimaging, and genetic analyses were evaluated. Whole exome sequencing (WES) was performed in three sporadic cases, while targeted CMT gene panel testing was used for two siblings. Variants were interpreted using ACMG guidelines, supported by public databases (ClinVar, HGMD, and VarSome), and confirmed by Sanger sequencing when available. Results: All had absent deep tendon reflexes and distal muscle weakness; three had intellectual disability. One patient was found to carry a novel homozygous frameshift variant (c.2568_2569del) in the IGHMBP2 gene, consistent with CMT2S. Other variants were identified in the NEFH (CMT2CC), DYNC1H1 (CMT2O), and MPV17 (CMT2EE) genes. Notably, a previously unreported co-occurrence of MPV17 mutation and congenital heart disease was observed in one case. Conclusions: This study expands the clinical and genetic spectrum of pediatric axonal CMT and highlights the role of early physical examination and molecular diagnostics in detecting rare variants. Identification of a novel IGHMBP2 variant and unique phenotypic associations provides new insights for future genotype–phenotype correlation studies. Full article