Introduction: Parkinson's disease (PD) is a prevalent neurodegenerative disorder, with several proposed pathogenic mechanisms. Given the established role of mitochondrial dysfunction in PD, this study seeks to investigate the enrichment of rare genetic variants tied to mitochondrial metabolism in cases of early-onset and familial PD. Methods: We performed a retrospective analysis on 248 early-onset and familial PD patients and 1622 control individuals. We assessed both pathway-level and gene-level burden of germline rare variants detected using exome sequencing in 467 nuclear genes related to mitochondrial metabolism. Results: Gene-set mutation burden analysis indicated an increased burden in genes associated with mtDNA maintenance. In addition, gene-level analysis identified a possible association between PD and rare variant burden in 14 mitochondrial metabolism-related genes under dominant or recessive inheritance models. Conclusions: Our findings support a potential contribution of rare germline variants affecting mitochondrial metabolism to the susceptibility in early-onset and familial PD.

We recently established an external quality assessment (EQA) scheme for next-generation sequencing (NGS) diagnostics in rare neurological disorders (RND) in collaboration with the EMQN. The first assessment rounds revealed limitations and variability in the quality and completeness of genetic testing reports. To improve and harmonize reporting in NGS-based diagnostics for RND, we identified 28 topics requiring recommendations based on EQA findings. These topics were grouped into four areas: clinical information, interpretation, methodology, and reporting. A team of 31 experts with relevant expertise was formed. Using an adapted Delphi approach, two rounds of surveys were conducted to prioritize the topics. Subsequently, area-specific expert groups met to formulate recommendations, followed by a final approval round using the five-finger consensus method involving all experts. In both Delphi rounds, all topics were rated as either very important (n = 12) or important (n = 16), and all were advanced for recommendation development. Consensus recommendations were achieved for 27 of the 28 topics. These include guidance on gene panel composition and updating, addressing disease-specific limitations of NGS (e.g., repeat expansion disorders), defining minimal quality parameters, and promoting sharing of variant interpretations. Each recommendation is supported by real-world examples. Due to differences in national healthcare frameworks and policies, consensus could not be reached regarding which patients should or should not undergo NGS testing. The dissemination of these recommendations is expected to improve the quality of genetic testing and reporting in RND diagnostics, promoting harmonization across laboratories and enabling easier comparison and interpretation of genetic testing reports.

BACKGROUND AND AIMS:Hereditary neuropathies are a group of genetically and phenotypically heterogeneous neuropathies. These are classified into: hereditary sensory motor neuropathy (HSMN) aka Charcot-Marie-Tooth disease (CMT), distal motor neuropathy (dMN), hereditary sensory autonomic neuropathy (HSAN), episodic neuropathies and polyneuropathy as part of a complex clinical presentation. The aim of this study was to determine final diagnoses in patients referred from the tertiary center in Serbia under suspicion of hereditary neuropathy. METHODS AND MATERIALS:This research included 340 patients directed for genetic testing from the Neurology Clinic, University Clinical Center of Serbia during the period from 2009 to 2023, who underwent complete genetic analyses available. RESULTS:The most prominent demyelinating neuropathy was group consisted of patients with CMT1A (93 (27.3%)), followed by CMT1B (10 (2.9%)). In the group of patients with axonal form of the disease, the most prevalent was the one with pathogenic variant in HINT1 (18 (5.3%)). Nineteen (5.6%) patients have had variants in GJB1 gene. DMN group was composed of seven (2%) patients. HSAN was final diagnosis in 2 (0.6%) patients. Group of 16 (4.7%) patients have had neuropathy as part of a complex clinical presentation. In 70 (20.6%) patients no significant genetic variant was found, even though clinical presentation was highly suggestive of hereditary neuropathy. INTERPRETATION:In line with other populations, CMT1A was the most common cause of hereditary neuropathy in Serbia. The axonal cohort predominantly included patients with variants in the HINT1 gene, which represents a population-specific characteristic. These findings highlight the importance of targeted genetic analysis in diagnosing hereditary neuropathies in certain populations.

Background/Objectives: Glomerulonephritis (GNs) is a heterogeneous group of inflammatory kidney diseases. Novel genetic methods have revealed some disease-causing and susceptibility genes underlying primary and secondary GNs. We aimed to investigate the presence of the single nucleotide polymorphisms (SNPs) rs12917707, found in the UMOD gene, and rs17319721, found in the SHROOM3 gene, as well as different polymorphisms in immune system genes in a group of children with GN. Method: The study included 71 children with GN (40 with primary and 31 with secondary GN) and 119 healthy children (HC). SNPs of the UMOD (rs12917707), SHROOM3 (rs17319721), IL10 (rs1800871 and rs3024505), IL6 (rs1800795), IL12B (rs3212227), IL23R (rs11209026 and rs1800896), and TNF (rs361525 and rs1800629) genes were genotyped. Results: The median age of the patients was 8 years at the onset of GN and 14 years at sampling. Allele A for rs1800629 in the TNF gene was more common in patients with GN in comparison to HCs (p = 0.009), followed by the difference in genotype distributions (p = 0.021), where AA and GA genotypes were more prevalent in patients. We found a statistically significant difference in haplotype distributions between patients and HCs for TNF, with GN patients having the GGAG haplotype more frequently and HCs having GGGG (p < 0.05). No correlation between the investigated SNPs and patient clinical characteristics (disease onset, primary or secondary GN, severity of disease, occurrence of remission, and presence of hypertension) was observed. Conclusions: An association between the TNF gene and different types of GN was noticed in children with GN. This may help us to understand the pathogenesis of these disorders and develop new treatments to cover the unmet needs of children with GN.

Background: Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are recognized as a spectrum of neurodegenerative disorders with overlapping clinical, pathological, and genetic features. The identification of C9orf72 hexanucleotide repeat expansion as the most common genetic cause of both conditions has prompted further investigation of genetic modifiers that may contribute to disease heterogeneity. We aimed to analyze the frequency of C9orf72 repeat expansions and potential modifying roles of APOE, ATXN1, and ATXN2 in Serbian ALS/FTD patients. Methods: Our study included an ALS/FTD cohort (n = 22) and healthy controls (n = 94). Repeat sizing in C9orf72, ATXN1 and ATXN2 was performed by fluorescent polymerase chain reaction (PCR) and capillary electrophoresis, while repeat-primed PCR was used to confirm C9orf72 expansions. APOE genotyping was conducted using real-time PCR assays targeting SNPs rs429358 and rs7412. Results: In the ALS/FTD cohort, 31.82% of the patients had heterozygous C9orf72 repeat expansion. The most common APOE genotype among patients was ε3/ε3 (72.73%). Intermediate-length ATXN1 alleles (32–44 repeats) were detected in 13.64% of patients and ATXN2 intermediate-length alleles (27–33 repeats) were found in 9% of patients. No significant differences were observed between ALS/FTD patients and controls in APOE ε4 frequency or intermediate ATXN1/ATXN2 repeats. Conclusions: Larger, population-specific studies and meta-analyses are needed to better understand the role of genetic modifiers in ALS/FTD pathogenesis and their influence on clinical heterogeneity. By integrating genetic and clinical data, this study represents a step toward the development of precision medicine strategies for ALS/FTD.

Introduction:High-throughput sequencing methods revealed disease-causing and susceptibility genes underlying glomerulonephritis (GN). Genetic disorders mimicking GN may be diagnosed in this way. The aim of this study was to perform whole-exome sequencing (WES) in a cohort of sporadic pediatric patients diagnosed with primary or secondary GN. Method:Thirty-one patients with GN and 50 nephrologically and immunologically healthy pediatric patients (control group - CG) were genetically analyzed. Allele frequencies were compared with the GnomAD database. WES was performed in the laboratory 3billion in South Korea. Results:Among 10 patients with primary GN, two patients were positive on WES (20%). One had a likely pathogenic heterozygous variant in the COL4A3 gene associated with Alport syndrome, and one had a heterozygous novel variant of uncertain significance in the CD46 gene associated with atypical hemolytic uremic syndrome (aHUS). In two of 14 patients with systemic lupus erythematosus (SLE) and GN, a heterozygous pathogenic variant (c.841_849 + 19del) in the C2 gene was detected. We found no significant variants in seven patients with Henoch-Schönlein purpura (HSP) and GN. Conclusion:WES helped us detect hereditary diseases that have a clinical presentation like GN, including Alport syndrome and possible aHUS. Finding susceptibility genes in GN helped us understand disease pathophysiology.

Clubfoot is recognized as one of the most frequent musculoskeletal deformities. Being characterized by equinus and varus hindfoot, adduction and inversion of the forefoot, cavus and calf muscles’ atrophy, it occurs in 1 to 2 per 1000 newborns. The concrete etiology of the deformity is not completely known but different studies suggest multifactorial pathogenesis, including numerous genetic and environmental risk factors. The most frequent clubfoot clinical presentation is isolated while it may also be associated with other neurologic conditions as part of a syndrome. The disease is easy seen at birth and its degree may vary from mild to an extremely rigid foot that is not reducible to manipulation. The challenge of identifyng the best clubfoot treatment method has become less demanding as Ponseti invented his method that is today thought to be the gold standard, including weekly stretching and casting while following tenotomy of the Achilles tendon is mandatory for rigid equinus. Foot abduction brace treatment for four to five years is indicated to prevent relapse. Surgical soft-tissue releases might be necessary for those resistant clubfeet, where conservative treatment is not sufficient. If untreated, clubfoot leads to lifelong disability, so it is essential to aware parents of the importance of persistent and patient commitment and compliance during the treatment period. This paper aims to show the significance of multifactorial clubfoot etiology as well as different clubfoot therapeutic modalities.

The GBA1 related Parkinson’s disease (PD) is associated with more severe non-motor symptoms. To date, studies of the role of GBA1 mutations in the occurrence of impulse control behaviours (ICBs) in PD have yielded controversial results. Our aim was to investigate the frequency and characteristics of ICBs in PD patients with GBA1 mutations. 213 consecutive PD patients were included. Clinical data were gathered via interviews and using the standard set of questionnaires. Genetic analysis of exons 8–11 of the GBA1 gene was performed for all participants. GBA1 variants were detected in 32 out of 213 patients (GBA-PD). ICBs were more frequent in GBA-PD (31.2

The ABC and ACMG variant classification systems were compared by asking mainly European clinical laboratories to classify variants in 10 challenging cases using both systems, and to state if the variant in question would be reported as a relevant result or not as a measure of clinical utility. In contrast to the ABC system, the ACMG system was not made to guide variant reporting but to determine the likelihood of pathogenicity. Nevertheless, this comparison is justified since the ACMG class determines variant reporting in many laboratories. Forty-three laboratories participated in the survey. In seven cases, the classification system used did not influence the reporting likelihood when variants labeled as “maybe report” after ACMG-based classification were included. In three cases of population frequent but disease-associated variants, there was a difference in favor of reporting after ABC classification. A possible reason is that ABC step C (standard variant comments) allows a variant to be reported in one clinical setting but not another, e.g., based on Bayesian-based likelihood calculation of clinical relevance. Finally, the selection of ACMG criteria was compared between 36 laboratories. When excluding criteria used by less than four laboratories (<10%), the average concordance rate was 46%. Taken together, ABC-based classification is more clear-cut than ACMG-based classification since molecular and clinical information is handled separately, and variant reporting can be adapted to the clinical question and phenotype. Furthermore, variants do not get a clinically inappropriate label, like pathogenic when not pathogenic in a clinical context, or variant of unknown significance when the significance is known.

Hereditary spastic paraplegia (HSP) is a group of neurodegenerative diseases with a high genetic and clinical heterogeneity. Numerous HSP patients remain genetically undiagnosed despite screening for known genetic causes of HSP. Therefore, identification of novel variants and genes is needed. Our previous study analyzed 74 adult Serbian HSP patients from 65 families using panel of the 13 most common HSP genes in combination with a copy number variation analysis. Conclusive genetic findings were established in 23 patients from 19 families (29%). In the present study, nine patients from nine families previously negative on the HSP gene panel were selected for the whole exome sequencing (WES). Further, 44 newly diagnosed adult HSP patients from 44 families were sent to WES directly, since many studies showed WES may be used as the first step in HSP diagnosis. WES analysis of cohort 1 revealed a likely genetic cause in five (56%) of nine HSP families, including variants in the ETHE1 , ZFYVE26 , RNF170 , CAPN1 , and WASHC5 genes. In cohort 2, possible causative variants were found in seven (16%) of 44 patients (later updated to 27% when other diagnosis were excluded), comprising six different genes: SPAST , SPG11 , WASCH5 , KIF1A , KIF5A , and ABCD1 . These results expand the genetic spectrum of HSP patients in Serbia and the region with implications for molecular genetic diagnosis and future causative therapies. Wide HSP panel can be the first step in diagnosis, alongside with the copy number variation (CNV) analysis, while WES should be performed after.

BACKGROUND AND OBJECTIVES:Maternal obesity influences pregnancy course in several different manners, and imbalanced nutrition during pregnancy may lead to various adverse pregnancy outcomes. Additionally, nutritional status during pregnancy may have implications for the health of the offspring and may possibly influence early motor development in children. The aim of this study was to assess the impact of excessive gestational weight gain (EGWG) on pregnancy outcomes and infant's motor development within the first twelve months of life. MATERIALS AND METHODS:The study included 200 participants divided in two groups based on their gestational weight gain. Maternal, perinatal, and neonatal factors were analyzed, and early motor development was assessed using the Alberta infant motor scale (AIMS). RESULTS:EGWG was significantly associated with: pre-pregnancy BMI (p < 0.001), family history for cardiovascular diseases (p = 0.013) and diabetes mellitus (p = 0.045), hypertensive disorder of pregnancy (p = 0.003), gestational diabetes mellitus (p < 0.001), gestational anemia (p = 0.001), vitamin D deficiency (p = 0.001), metformin use (p = 0.045), pre-labor premature rupture of membranes (p = 0.031), amniotic fluid index (p = 0.047), and APGAR score in the first five min of life (p = 0.007). Scored by AIMS, EGWG was significantly associated with parameters of early motor development at the age of three AIMS total (p < 0.001), six AIMS total (p < 0.001), nine AIMS total (p < 0.001), and twelve AIMS total (p < 0.001) months of infant's life. CONCLUSIONS:The link between EGWG and adverse neurodevelopmental outcomes in offspring is a complex and multifaceted issue. Our results imply significant alterations in early motor development in the group of infants born from mothers who gained weight excessively during pregnancy. Further studies are needed to unravel the intricacies of this relationship and inform strategies for preventive interventions and supportive care during pregnancy and infancy.

Exome sequencing (ES) may identify and report secondary findings that are unrelated to the primary disease for which the patient underwent genetic testing, but are of potential value in patient care. In this study, we evaluated 81 American College of Medical Genetics (ACMG) medically actionable genes in 443 patients with various neurological disorders. The variants identified were classified and reported following the 2015 ACMG Standards and Guidelines for the interpretation of sequence variants and the ACMG recommendations for reporting secondary findings (v3.2). We detected a total of 17 variants in 17 patients across 9 different genes as secondary findings. Seven heterozygous variants were found in BRCA1, MSH2 , and PALB2 which are part of the cancer phenotype category. Nine heterozygous variants were found in MYH7 , TTN , LDLR , DSC2 , and DSP which are part of the cardiovascular phenotype category. Finally, one heterozygous variant was found in TTR which is part of the miscellaneous phenotype category. Thirteen of above mentioned variants were classified as known pathogenic and four as expected pathogenic. The information collected in our study may lead to the prevention of severe morbidity and mortality and provides additional insight into the genetic background of the Serbian population.

Background: Recognized as one of the most serious musculoskeletal deformities, occurring in 1–2 per 1000 newborns, 80% of clubfeet are idiopathic while 20% present with associated malformations. The etiopathogenesis of clubfoot is described as multifactorial, including both genetic and environmental risk factors. The aim of this study was to analyze possible genetic causes of isolated and syndromic clubfoot in Serbian children, as well as to correlate clinical and genetic characteristics that would provide insight into clubfoot etiopathogenesis and possibly contribute to global knowledge about clinical features of different genetically defined disorders. Methods: We evaluated 50 randomly selected, eligible children with clubfoot aged 3 to 16 years that were initially hospitalized and treated at University Children’s Hospital between November 2006 and November 2022. The tested parameters were gender, age, dominant foot, affected foot, degree of deformity, treatment, neuromuscular disorders, positive family history, and maternal smoking. According to the presence of defined genetic mutation/s by whole exome sequencing (WES), patients were separated into two groups: positive (with genetic mutation/s) and negative (without genetic mutation/s). Results: Seven patients were found to be positive, i.e., with genetic mutation/s. A statistically significant difference between categorical variables was found for families with a history of clubfoot, where more than half (57.14%) of patients with confirmed genetic mutation/s also had a family history of genetic mutation/s (p = 0.023). Conclusions: The results from this study further expand the genetic epidemiology of clubfoot. This study contributes to the establishment of genetic diagnostic strategies in pediatric patients with this condition, which can lead to more efficient genetic diagnosis.

Background: Mitochondrial diseases are a group of disorders caused by dysfunction of mitochondria - the organelles that generate energy for the cell by converting the energy of food molecules into the ATP that powers most cell functions. Mitochondrial diseases are one of the most common groups of rare diseases with a minimum prevalence of greater than 1 in 5000 in adults. Clinical manifestations of mitochondrial diseases are heterogonous, mostly affecting nervous and muscle systems and sensory organs; symptoms can appear at birth or they may not appear until adulthood These diseases have genetic basis, and could be caused by mutations in nuclear genes, as well as by mutations in mitochondrial DNA (mtDNA) - small, maternally inherited, DNA molecule. An additional aspect of their genetic complexity is given by phenomenon of mtDNA heteroplasmy. Having all this in mind, the detection of the causative gene mutation is of crucial importance for diagnostics and further management of mitochondrial diseases. In addition, development of new therapeutic strategies is based on best knowledge ate genomic level. Methods and objectives: Genetic analyses were performed at patients suspect with mitochondrial diseases in order to detect causative gene mutations. Applied methods were targeted sequencing of mtDNA and clinical exome analysis by next generation sequencing. Results: In this report we will present our experience with genetic testing of mitochondrial diseases, challenges in genetic counselling, and possible new therapeutic options in mitochondrial diseases. Conclusion: Modern management of mitochondrial diseases is based on their genetic diagnostics. Contemporary algorithms and guidelines should be applied in this field of rare diseases.

Pediatric stroke (PS) is an injury caused by the occlusion or rupture of a blood vessel in the central nervous system (CNS) of children, before or after birth. Hemiparesis is the most common motoric deficit associated with PS in children. Therefore, it is important to emphasize that PS is a significant challenge for rehabilitation, especially since the consequences may also appear during the child’s growth and development, reducing functional capacity. The plasticity of the child’s CNS is an important predecessor of recovery, but disruption of the neural network, specific to an immature brain, can have harmful and potentially devastating consequences. In this review, we summarize the complexity of the consequences associated with PS and the possibilities and role of modern rehabilitation. An analysis of the current literature reveals that Constraint-Induced Movement Therapy, forced-use therapy, repetitive transcranial magnetic stimulation, functional electrical stimulation and robot-assisted therapy have demonstrated at least partial improvements in motor domains related to hemiparesis or hemiplegia caused by PS, but they are supported with different levels of evidence. Due to the lack of randomized controlled studies, the optimal rehabilitation treatment is still debatable, and therefore, most recommendations are primarily based on expert consensuses, opinions and an insufficient level of evidence.

Introduction. Histopathological findings of various inclusions were reported in the central nervous system of amyotrophic lateral sclerosis (ALS) patients but not in the peripheral nerves. Case report. We present a 66-year-old man with lower limb weakness, with later development of weakness in the upper limbs and loss of sphincter control. Neurological examination showed the affection of both upper and lower motor neurons. He had paresthesia on the left side of his body and socks-distribution numbness. Histopathology of the sural nerve and genetic report showed basophilic periodic acid-Schiff (PAS)-positive intra-axonal inclusions and heterozygous L144F mutation in the exon 5 of the SOD1 gene. Conclusion. It seems that the presence of the basophilic peripheral nerve inclusions may suggest a diagnosis of SOD1-positive ALS.