Browsing by Author "Maver, Ales (22135394900)"

Background: The study presents a detailed examination and follow-up of a Slovenian patient with an Leber Hereditary Optic Neuropathy (LHON)-like phenotype and bilateral optic neuropathy in whom genetic analysis identified a novel variant MT-CYB:m.15309T>C (Ile188Thr). Methods: We provide detailed analysis of the clinical examinations of a male patient with bilateral optic neuropathy from the acute stage to 8 years of follow-up. Complete ophthalmological exam, electrophysiology and optical coherence tomography (OCT) segmentation were performed. The genotype analysis was performed with a complete screening of the mitochondrial genome. Furthermore, proteomic analysis of the protein structure and function was performed to assess the pathogenicity of a novel variant of unknown significance. Mitochondrial function analysis of the patient’s peripheral blood mononuclear cells (PBMCs) was performed with the objective of evaluating the mutation effect on mitochondrial function using flow cytometry and high-resolution respirometry. Results: The patient had a profound consecutive bilateral visual loss at 19 years of age due to optic neuropathy with characteristics of LHON; however, unlike patients with typical LHON, the patient experienced a fluctuation in visual function and significant late recovery. He had a total of three visual acuity deteriorations and improvements in the left eye, with concomitant visual loss in the right eye and a final visual acuity drop reaching nadir 9 months after onset. The visual loss was characterized by centrocecal scotoma, abnormal color vision and abnormal VEP, while deterioration of PERG N95 followed with a lag of several months. The OCT examination showed retinal nerve fiber layer thinning matching disease progression. Following a two-year period of legal blindness, the patient’s visual function started to improve, and over the course of 5 years, it reached 0.5 and 0.7 Snellen (0.3 and 0.15 LogMAR) visual acuity (VA). Mitochondrial sequencing identified a presumably pathogenic variant m.15309T>C in the MT-CYB gene at 65% heteroplasmy, belonging to haplogroup K. Mitochondrial function assessment of the patient’s PBMCs showed a lower respiration rate, an increase in reactive oxygen species production and the presence of mitochondrial depolarization, compared to an age- and sex-matched healthy control’s PBMCs. Conclusions: A novel variant in the MT-CYB:m.15309T>C (Ile188Thr) gene was identified in a patient with optic nerve damage and the LHON phenotype without any additional systemic features and atypical presentation of the disease with late onset of visual function recovery. The pathogenicity of the variant is supported by proteomic analysis and the mitochondrial dysfunction observed in the patient’s PBMCs. © 2025 by the authors.

Background: The study presents a detailed examination and follow-up of a Slovenian patient with an Leber Hereditary Optic Neuropathy (LHON)-like phenotype and bilateral optic neuropathy in whom genetic analysis identified a novel variant MT-CYB:m.15309T>C (Ile188Thr). Methods: We provide detailed analysis of the clinical examinations of a male patient with bilateral optic neuropathy from the acute stage to 8 years of follow-up. Complete ophthalmological exam, electrophysiology and optical coherence tomography (OCT) segmentation were performed. The genotype analysis was performed with a complete screening of the mitochondrial genome. Furthermore, proteomic analysis of the protein structure and function was performed to assess the pathogenicity of a novel variant of unknown significance. Mitochondrial function analysis of the patient’s peripheral blood mononuclear cells (PBMCs) was performed with the objective of evaluating the mutation effect on mitochondrial function using flow cytometry and high-resolution respirometry. Results: The patient had a profound consecutive bilateral visual loss at 19 years of age due to optic neuropathy with characteristics of LHON; however, unlike patients with typical LHON, the patient experienced a fluctuation in visual function and significant late recovery. He had a total of three visual acuity deteriorations and improvements in the left eye, with concomitant visual loss in the right eye and a final visual acuity drop reaching nadir 9 months after onset. The visual loss was characterized by centrocecal scotoma, abnormal color vision and abnormal VEP, while deterioration of PERG N95 followed with a lag of several months. The OCT examination showed retinal nerve fiber layer thinning matching disease progression. Following a two-year period of legal blindness, the patient’s visual function started to improve, and over the course of 5 years, it reached 0.5 and 0.7 Snellen (0.3 and 0.15 LogMAR) visual acuity (VA). Mitochondrial sequencing identified a presumably pathogenic variant m.15309T>C in the MT-CYB gene at 65% heteroplasmy, belonging to haplogroup K. Mitochondrial function assessment of the patient’s PBMCs showed a lower respiration rate, an increase in reactive oxygen species production and the presence of mitochondrial depolarization, compared to an age- and sex-matched healthy control’s PBMCs. Conclusions: A novel variant in the MT-CYB:m.15309T>C (Ile188Thr) gene was identified in a patient with optic nerve damage and the LHON phenotype without any additional systemic features and atypical presentation of the disease with late onset of visual function recovery. The pathogenicity of the variant is supported by proteomic analysis and the mitochondrial dysfunction observed in the patient’s PBMCs. © 2025 by the authors.

Purpose: We sought to determine the analytical sensitivity of several extended exome variation analysis approaches in terms of their contribution to diagnostic yield and their clinical feasibility. Methods: We retrospectively analyzed the results of genetic testing in 1,059 distinct cases referred for exome sequencing to our institution. In these, we routinely employed extended exome analysis approaches in addition to basic variant analysis, including (i) copy-number variation (CNV) detection, (ii) nonconsensus splice defect detection, (ii) genomic breakpoint detection, (iv) homozygosity mapping, and (v) mitochondrial variant analysis. Results: Extended exome analysis approaches assisted in identification of causative genetic variant in 44 cases, which represented a 4.2% increase in diagnostic yield. The greatest contribution was associated with CNV analysis (1.8%) and splice variant prediction (1.2%), and the remaining approaches contributed an additional 1.2%. Analysis of workload has shown that on average nine additional variants per case had to be interpreted in the extended analysis. Conclusion: We show that extended exome analysis approaches improve the diagnostic yield of heterogeneous genetic disorders and result in considerable increase of diagnostic yield of exome sequencing with a minor increase of interpretative workload. © 2018 American College of Medical Genetics and Genomics.

Clinical exome sequencing is currently being used in diagnostics of various genetic disorders, but studies supporting its application in clinical setting are scarce. The aim of this study was to establish diagnostic and clinical utility of clinical exome sequencing in patients with moderate and severe global developmental delay/intellectual disability. Clinical diagnosis was made in 49 of 88 investigated patients, with overall diagnostic yield of 55.7%. Molecular findings are characterized in detail, including the impact of newly made diagnosis on clinical management. Several previously unreported genotype-phenotype correlations and 33 novel variants are described. Genetic and clinical data were shared through publicly available database. In conclusion, clinical exome sequencing allows identification of causative variants in a significant proportion of patients in investigated clinical subgroup. Compared to whole exome sequencing, it shows similar diagnostic and clinical utility with reduced costs, which could be of particular importance for institutions with limited resources. © The Author(s) 2019.

Purpose: In recent years, many genes have been associated with male infertility; however, testing of monogenic forms has not yet been clinically implemented in the diagnosis of severe forms of idiopathic male infertility, as the diagnostic utility has not been established yet. The aim of this study was therefore to answer if the implementation of genetic testing for monogenic forms of male infertility could contribute to the clinical diagnosis of men with severe forms of idiopathic male infertility. Materials and Methods: Based on the ClinGene curation protocol, we defined a panel of genes with sufficient evidence for the involvement with severe male infertility. We tested the 21-gene panel in a representative multicentric cohort of men with significantly impaired spermatogenesis. We performed whole exome sequencing on 191 infertile men with severe forms of idiopathic male infertility; non-obstructive azoospermia, and severe oligozoospermia (<5 million spermatozoa/mL). The control group consisted of 216 men who fathered a child. DNA was prepared based on the Twist CORE exome protocol and sequenced on the Illumina NovaSeq 6000 platform. Variants were classified using the Association for Clinical Genomic Science (ACGS) Best Practice Guidelines for Variant Classification in Rare Disease 2020. Results: We identified potential monogenic disease-causing variants in four infertile men. Pathogenic/likely pathogenic variants in STAG3 (c.2776C>T, p.Arg926*; c.2817delG, p.Leu940fs), MSH4 (c.1392delG, p.Ile465fs; c.2261C>T, p.Ser754Leu), TEX15 (c.6848_6849delGA, p.Arg2283fs; c.6271dupA, p.Arg2091fs), and TEX14 (c.1021C>T, p.Arg341*) genes were found. Conclusions: In the present multicentric cohort study, a monogenic cause in 2.1% of infertile men was identified. These findings confirm the utility of monogenic testing and suggest the clinical use of monogenic testing for men with severe forms of idiopathic male infertility. Copyright © 2025 Korean Society for Sexual Medicine and Andrology.

Purpose: In recent years, many genes have been associated with male infertility; however, testing of monogenic forms has not yet been clinically implemented in the diagnosis of severe forms of idiopathic male infertility, as the diagnostic utility has not been established yet. The aim of this study was therefore to answer if the implementation of genetic testing for monogenic forms of male infertility could contribute to the clinical diagnosis of men with severe forms of idiopathic male infertility. Materials and Methods: Based on the ClinGene curation protocol, we defined a panel of genes with sufficient evidence for the involvement with severe male infertility. We tested the 21-gene panel in a representative multicentric cohort of men with significantly impaired spermatogenesis. We performed whole exome sequencing on 191 infertile men with severe forms of idiopathic male infertility; non-obstructive azoospermia, and severe oligozoospermia (<5 million spermatozoa/mL). The control group consisted of 216 men who fathered a child. DNA was prepared based on the Twist CORE exome protocol and sequenced on the Illumina NovaSeq 6000 platform. Variants were classified using the Association for Clinical Genomic Science (ACGS) Best Practice Guidelines for Variant Classification in Rare Disease 2020. Results: We identified potential monogenic disease-causing variants in four infertile men. Pathogenic/likely pathogenic variants in STAG3 (c.2776C>T, p.Arg926*; c.2817delG, p.Leu940fs), MSH4 (c.1392delG, p.Ile465fs; c.2261C>T, p.Ser754Leu), TEX15 (c.6848_6849delGA, p.Arg2283fs; c.6271dupA, p.Arg2091fs), and TEX14 (c.1021C>T, p.Arg341*) genes were found. Conclusions: In the present multicentric cohort study, a monogenic cause in 2.1% of infertile men was identified. These findings confirm the utility of monogenic testing and suggest the clinical use of monogenic testing for men with severe forms of idiopathic male infertility. Copyright © 2025 Korean Society for Sexual Medicine and Andrology.

Purpose: Common diagnostic next-generation sequencing strategies are not optimized to identify inherited variants in genes associated with dominant neurodevelopmental disorders as causal when the transmitting parent is clinically unaffected, leaving a significant number of cases with neurodevelopmental disorders undiagnosed. Methods: We characterized 21 families with inherited heterozygous missense or protein-truncating variants in CHD3, a gene in which de novo variants cause Snijders Blok-Campeau syndrome. Results: Computational facial and Human Phenotype Ontology–based comparisons showed that the phenotype of probands with inherited CHD3 variants overlaps with the phenotype previously associated with de novo CHD3 variants, whereas heterozygote parents are mildly or not affected, suggesting variable expressivity. In addition, similarly reduced expression levels of CHD3 protein in cells of an affected proband and of healthy family members with a CHD3 protein-truncating variant suggested that compensation of expression from the wild-type allele is unlikely to be an underlying mechanism. Notably, most inherited CHD3 variants were maternally transmitted. Conclusion: Our results point to a significant role of inherited variation in Snijders Blok-Campeau syndrome, a finding that is critical for correct variant interpretation and genetic counseling and warrants further investigation toward understanding the broader contributions of such variation to the landscape of human disease. © 2022 American College of Medical Genetics and Genomics

Background: Noonan syndrome (NS) is a congenital genetic disorder with a prevalence of 1 in 1000 to 2500 live births, and is characterized by distinctive facial features, short stature, chest deformities, and congenital heart disease. This study aims to evaluate the prevalence of specific genetic mutations and their impact on cardiovascular and other outcomes in NS. Methods: We conducted a retrospective clinical study of 25 pediatric patients diagnosed with NS at two institutions: The Mother and Child Health Care Institute of Serbia and the Clinic for Children Diseases, University Clinical Center of the Republic of Srpska. Patients underwent whole-exome sequencing (WES) to identify genetic mutations. Clinical data, including cardiovascular manifestations, psychomotor development, and stature, were analyzed in relation to mutation types. Results: The cohort comprised 60% male and 40% female patients, with a median age at diagnosis of 7.2 years. Cardiovascular abnormalities were present in 88% of patients. Mutations in PTPN11 were most commonly associated with pulmonary valve stenosis (PVS), while RAF1 mutations were prevalent in patients with hypertrophic cardiomyopathy (HCM). No significant association was found between cardiac disease and delayed psychomotor development (p = 0.755), even though the likelihood ratio showed significance in that regard (p = 0.018). Short stature was observed in 48% of patients but was not significantly correlated with genetic type of disease, presence of cardiac disease, or developmental delay. Conclusions: The study confirms the high prevalence of cardiovascular manifestations in NS and highlights genotype–phenotype correlations. While cardiac abnormalities are common, their impact on psychomotor development and stature is less clear. Further research is needed to explore genetic interactions influencing these outcomes and refine clinical management strategies. © 2024 by the authors.

Background: Noonan syndrome (NS) is a congenital genetic disorder with a prevalence of 1 in 1000 to 2500 live births, and is characterized by distinctive facial features, short stature, chest deformities, and congenital heart disease. This study aims to evaluate the prevalence of specific genetic mutations and their impact on cardiovascular and other outcomes in NS. Methods: We conducted a retrospective clinical study of 25 pediatric patients diagnosed with NS at two institutions: The Mother and Child Health Care Institute of Serbia and the Clinic for Children Diseases, University Clinical Center of the Republic of Srpska. Patients underwent whole-exome sequencing (WES) to identify genetic mutations. Clinical data, including cardiovascular manifestations, psychomotor development, and stature, were analyzed in relation to mutation types. Results: The cohort comprised 60% male and 40% female patients, with a median age at diagnosis of 7.2 years. Cardiovascular abnormalities were present in 88% of patients. Mutations in PTPN11 were most commonly associated with pulmonary valve stenosis (PVS), while RAF1 mutations were prevalent in patients with hypertrophic cardiomyopathy (HCM). No significant association was found between cardiac disease and delayed psychomotor development (p = 0.755), even though the likelihood ratio showed significance in that regard (p = 0.018). Short stature was observed in 48% of patients but was not significantly correlated with genetic type of disease, presence of cardiac disease, or developmental delay. Conclusions: The study confirms the high prevalence of cardiovascular manifestations in NS and highlights genotype–phenotype correlations. While cardiac abnormalities are common, their impact on psychomotor development and stature is less clear. Further research is needed to explore genetic interactions influencing these outcomes and refine clinical management strategies. © 2024 by the authors.

This study delves into the diagnostic yield of whole-exome sequencing (WES) in pediatric patients presenting with developmental delay/intellectual disability (DD/ID), while also exploring the utility of Reverse Phenotyping (RP) in refining diagnoses. A cohort of 100 pediatric patients underwent WES, yielding a diagnosis in 66% of cases. Notably, RP played a significant role in cases with negative prior genetic testing, underscoring its significance in complex diagnostic scenarios. The study revealed a spectrum of genetic conditions contributing to DD/ID, illustrating the heterogeneity of etiological factors. Despite challenges, WES demonstrated effectiveness, particularly in cases with metabolic abnormalities. Reverse phenotyping was indicated in half of the patients with positive WES findings. Neural network models exhibited moderate-to-exceptional predictive abilities for aiding in patient selection for WES and RP. These findings emphasize the importance of employing comprehensive genetic approaches and RP in unraveling the genetic underpinnings of DD/ID, thereby facilitating personalized management and genetic counseling for affected individuals and families. This research contributes insights into the genetic landscape of DD/ID, enhancing our understanding and guiding clinical practice in this particular field of clinical genetics. © 2024 by the authors.

This study delves into the diagnostic yield of whole-exome sequencing (WES) in pediatric patients presenting with developmental delay/intellectual disability (DD/ID), while also exploring the utility of Reverse Phenotyping (RP) in refining diagnoses. A cohort of 100 pediatric patients underwent WES, yielding a diagnosis in 66% of cases. Notably, RP played a significant role in cases with negative prior genetic testing, underscoring its significance in complex diagnostic scenarios. The study revealed a spectrum of genetic conditions contributing to DD/ID, illustrating the heterogeneity of etiological factors. Despite challenges, WES demonstrated effectiveness, particularly in cases with metabolic abnormalities. Reverse phenotyping was indicated in half of the patients with positive WES findings. Neural network models exhibited moderate-to-exceptional predictive abilities for aiding in patient selection for WES and RP. These findings emphasize the importance of employing comprehensive genetic approaches and RP in unraveling the genetic underpinnings of DD/ID, thereby facilitating personalized management and genetic counseling for affected individuals and families. This research contributes insights into the genetic landscape of DD/ID, enhancing our understanding and guiding clinical practice in this particular field of clinical genetics. © 2024 by the authors.