Cascade testing (CT) is an effective instrument for identifying an index patient’s relatives at high risk of a heritable condition enabling informed decision-making on preventive interventions and reproductive choice. However, CT remains underutilised and faces barriers. Discussions are ongoing on how to optimise informing family members and testing uptake in a responsible manner. The European Society of Human Genetics (ESHG) contributes to this debate and provides recommendations based on an ethical analysis of when CT is justified, or may be less compelling, considering proportionality and the judicious use of finite resources. ESHG underscores the strong consensus regarding the ‘moral architecture’ of CT in cases of a high risk of serious, avoidable harm. In such cases, a more active approach towards CT is suggested, including a more directive approach in counselling, more active support for the proband, direct contacting, and balancing confidentiality when this is necessary to avoid a high risk of serious harm, taking account of national regulations and jurisdictions. In contrast, more caution is advised in more complex cases where the balance of benefits and harms of CT is less clear, such as when penetrance is low, and actionability or medical treatment is limited. This more cautious approach does not call for directivity, direct contact or the relaxing of medical confidentiality. The focus, then, shifts to cascade counselling, rather than cascade testing. In some cases, CT may not be proportional or appropriate given the balance between benefits and harms, also in view of available resources.

Background/Objectives: The Carpathian Basin is a genetically and culturally diverse region shaped by complex historical migrations and various ethnic groups. While studies based on Y-chromosomal and mitochondrial DNA have provided valuable insights into the genetic diversity of these populations, genome-wide autosomal SNP data remain underutilized in understanding the genetic structure of these groups. This study presents the first genome-wide autosomal SNP-based analysis of key Hungarian-speaking ethnic groups in the region, focusing on admixture patterns and the extent of preserved historical genetic components. Methods: We analyzed genome-wide autosomal SNP data from 597 individuals representing several ethnic groups in the Carpathian Basin. Standard population genetic methods were applied to assess genetic structure, admixture and differentiation, with comparisons to broader European reference populations. Results: Most ethnic groups displayed genetic affinities with Eastern European populations, consistent with historical and geographical proximity. The Swabian group, of German descent, exhibited a distinct Western European genetic component, likely due to historical isolation. Transylvanian populations appeared relatively homogeneous, indicating a shared ancestral background. In contrast, Csangos showed distinct sub-clusters, suggesting population isolation and distinct histories. Overall, genetic homogeneity characterizes the region, though certain isolated groups retain distinct ancestral signatures. Conclusions: Autosomal SNP analysis revealed mild overall genetic structuring among Carpathian Basin ethnic groups. However, historical isolation has preserved unique genetic components in specific groups, highlighting the value of genome-wide data in uncovering fine-scale population structure. These findings contribute to a deeper understanding of regional genetic diversity, which has implications for both population history and health-related genetic research.

BackgroundUndiagnosed rare diseases (URDs) are a complex and multifaceted challenge, especially in low-and medium-income countries. They affect individuals with unique clinical features and lack a clear diagnostic label. Although the Undiagnosed Diseases Network International (UDNI) definition of URDs is not universally accepted, it is widely recognized.MethodsWe surveyed UDNI members and participants from other countries to explore the challenges posed by URDs and identify possible solutions. Participation in the survey was completely voluntary.ResultsThe survey revealed a need for more consensus on a universally accepted definition for URDs. Still, the UDNI definition gained widespread recognition and serves as a valuable framework for understanding and addressing the challenges of URDs. In addition to national or international networks, fostering a more substantial engagement and resource-sharing ethos among member countries is critical. Despite advances in genomics and diagnostic tools, the diagnostic journey for people living with URDs (PLURDs) remains arduous and often inconclusive. The availability of specialized centers and the utilization of whole exome sequencing (WES) and whole genome sequencing (WGS) vary across countries, with disparities due to healthcare systems, economic status, and government policies. Advocacy groups play a crucial role in supporting PLURDs.ConclusionA unified commitment to prioritizing URDs on the global health agenda, paired with targeted funding, stipulated national strategies, and aligned international cooperation, is imperative to leveling the playing field for the diagnosis and management of URDs and capitalizing on the potential of Advocacy Groups as allies in this endeavor.

BACKGROUND/OBJECTIVES:The Seklers are a Hungarian-speaking regional population in Transylvania, Romania, with a long and complex history, yet comprehensive genome-wide studies remain limited. Our aim was to characterize the genetic background of multiple Sekler communities using high-density autosomal data and to place them in a broader Central and Eastern European context. METHODS:Here we analyzed genome-wide autosomal SNP data obtained from 17 Sekler groups. Allele frequency- and haplotype-based approaches were applied to assess overall genetic structure, ancestry patterns, recent shared ancestry, and signals of demographic history. RESULTS:Analyses based on overall allele-frequency patterns showed that Sekler groups fit into a single, coherent genetic cluster shared with Hungarians. No major differences were detected among the Sekler communities at this broader genomic level, and their genetic profiles were largely indistinguishable from one another. Using haplotype-based methods, most Sekler groups again formed a compact cluster. However, two villages, Deményháza and Nyárádszentimre, showed clear signs of increased within-group relatedness and subtle separation. These patterns might indicate that both communities experienced stronger local drift and reduced effective population size, while other Sekler groups showed no comparable deviation from the general regional pattern. CONCLUSIONS:Although a small number of villages display modest signs of localized demographic drift, our results support that the Seklers represent a regionally distinct and internally cohesive population, whose genetic structure is shaped mainly by common historical and linguistic ties, with minor village-level variation, forming a uniform part of the Hungarian-speaking population of the East-Central European region.

BACKGROUND:The Csangos are an East-Central European ethnographic group living mainly in east of Transylvania in Romania. Traditionally, ethnography distinguishes three Csango subpopulations, the Moldavian, Gyimes and Burzenland Csangos. In our previous study we found that the Moldavian Csangos have East Asian/Siberian Turkic ancestry components that might be unique in the East-Central European region and might help to better understand the history of Hungarian speaking ethnic groups of the area. Since then, we obtained further Csango samples from Moldavia and from a distinct region of Gyimes, which two Csango subgroups are traditionally different since they live in a degree of isolation not only from other people but also from each other. Here we present the first genomic analysis of Gyimes Csangos, which intended to compare the genetic makeup of these two Csango subgroups using both allele-frequency and haplotype-based methods. The main goal of the study was to investigate the genetic isolation of the Csangos on a genome-wide SNP basis and to assess the isolation of Gyimes Csangos, which in contrast to the Moldavians was not yet studied. RESULTS:Our results show that these two Csango groups show slight differences from each other. We confirmed the genetic isolation of Moldavian Csangos and revealed that Gyimes Csangos have a similar, but detectably weaker isolation. In the case of Gyimes Csangos we detected also a stronger East European or presumably Asian derived ancestry. CONCLUSION:The Gyimes Csangos show a degree of genetic isolation comparable to that of the Moldavians. The Asian ancestry that differentiates the Moldavian Csango people from the other East-Central European populations may be present in the Gyimes Csangos in an even higher degree, since Gyimes Csango individuals show a more significant share from that ancestry component.

BackgroundMarfan syndrome (MFS) is a clinically heterogeneous hereditary connective tissue disorder. Severe cardiovascular manifestations (i.e., aortic aneurysm and dissection) are the most life-threatening complications. Most of the cases are caused by mutations, a minor group of which are copy number variations (CNV), in the FBN1 gene. MethodsMultiplex ligation-dependent probe amplification test was performed to detect CNVs in 41 MFS patients not carrying disease-causing mutations in FBN1 gene. Moreover, the association was analyzed between the localization of CNVs, the affected regulatory elements and the cardiovascular phenotypes among all cases known from the literature. ResultsA large two-exon deletion (exon 46 and 47) was identified in two related patients, which was associated with a mild form of cardiovascular phenotype. Severe cardiovascular symptoms were found significantly more frequent in patients with FBN1 large deletion compared to our patients with intragenic small scale FBN1 mutation. Bioinformatic data analyses of regulatory elements located within the FBN1 gene revealed an association between the deletion of STAT3 transcription factor-binding site and cardiovascular symptoms in five out of 25 patients. ConclusionOur study demonstrated that large CNVs are often associated with severe cardiovascular manifestations in MFS and the localization of these CNVs affect the phenotype severity.

Background German-derived ethnicities are one of the largest ethnic groups in Hungary, dating back to the formation of the Kingdom of Hungary, which took place at the beginning of the 11th century. Germans arrived in Hungary in many waves. The most significant immigration wave took place following the collapse of the Ottoman Empire in East-Central Europe which closed the 150 year long Ottoman occupation. To date, there are no comprehensive genome-wide studies investigating the genetic makeup of the Danube Swabians. Here we analyzed 47 Danube Swabian samples collected from elderly Swabian individuals living in the Dunaszekcső-Bár area, in Danube side villages of Southwest Hungary. These Swabians, according to self-declaration, did not admix with other ethnic groups for 3–6 succeeding generations. Using Illumina Infinium 720 K Beadchip genotype data, we applied allele frequency-based and haplotype-based genome-wide marker data analyses to investigate the ancestry and genetic composition of the collected Danube Swabian samples. Results Haplotype-based analyses like identity by descent segment analysis show that the investigated Danube Swabians possess significant German and other West European ancestry, but their Hungarian ancestry is also prominent. Our results suggest that their main source of ancestry can be traced back to Western Europe, presumably to the region of Germany. Conclusion This is the first analysis of Danube Swabian population samples based on genome-wide autosomal data. Our results establish the basis for conducting further comprehensive research on Danube Swabians and on other German ethnicities of the Carpathian basin, which can help reconstruct their origin, and identify their major archaic genomic patterns.

Down syndrome (DS) is a leading human genomic abnormality resulting from the trisomy of chromosome 21. The genomic base of the aneuploidy behind this disease is complex, and this complexity poses formidable challenges to understanding the underlying molecular basis. In the spectrum of the classic DS risk factor associations, the role of nutrients, vitamins, and, in general, the foodborne-associated background, as part of the events ultimately leading to chromosome nondisjunction, has long been recognized as a well-established clinical association. The integrity of the microbiome is a basic condition in these events, and the dysbiosis may be associated with secondary health outcomes. The possible association of DS development with maternal gut microbiota should therefore require more attention. We have hypothesized that different classes of antibiotics might promote or inhibit the proliferation of different microbial taxa; and hence, we might find associations between the use of the different classes of antibiotics and the prevalence of DS through the modification of the microbiome. As antibiotics are considered major disruptors of the microbiome, it could be hypothesized that the consumption/exposure of certain classes of antibiotics might be associated with the prevalence of DS in European countries (N = 30). By utilizing three different statistical methods, comparisons have been made between the average yearly antibiotic consumption (1997–2020) and the estimated prevalence of people living with DS for the year 2019 as a percentage of the population in European countries. We have found strong statistical correlations between the consumption of tetracycline (J01A) and the narrow-spectrum, beta-lactamase-resistant penicillin (J01CF) and the prevalence of DS.

Introduction: Patients carrying interstitial deletions of the long arm of chromosome 9 show similar features. These phenotypes are often characterized by developmental delay, intellectual disability, short stature, and dysmorphism. Previously reported deletions differ in size and location spanning from 9q21 to 9q34 and were mostly detected by conventional cytogenetic techniques. Methods: Based on clinical features suggesting primarily chromosomal diseases, aCGH analysis was indicated. We report on de novo overlapping interstitial 9q deletions in 3 unrelated individuals presenting neurodevelopmental disorder and multiple congenital anomalies. Results: An 8.03-Mb (90 genes), a 15.71-Mb (193 genes), and a 15.81-Mb (203 genes) deletion were identified in 9q affecting 9q22.33q33.3. The overlapping region was 1.50 Mb, including 2 dosage-sensitive genes, namely EPB41L4B (OMIM #610340) and SVEP1 (OMIM #611691). These genes are thought to be involved in cellular adhesion, migration, and motility. The non-overlapping regions contain 24 dosage-sensitive genes. Conclusion: Besides the frequently described symptoms (developmental delay, intellectual disability, skeletal abnormalities, short stature, and dysmorphic facial features) shared by the patients with interstitial deletions of chromosome 9q reported thus far, two of our patients showed distinct forms of epilepsy, which were successfully treated, and one had a bilateral cleft lip and palate. Possible candidate genes for epilepsy and cleft lip and palate are discussed.

Purpose: Nonerythrocytic alpha II-spectrin (SPTAN1) variants have been previously associated with intellectual disability and epilepsy. We conducted this study to delineate the phenotypic spec-trum of SPTAN1 variants.Methods: We carried out SPTAN1 gene enrichment analysis in the rare disease component of the 100,000 Genomes Project and screened 100,000 Genomes Project, DECIPHER database, and GeneMatcher to identify individuals with SPTAN1 variants. Functional studies were performed on fibroblasts from 2 patients. Results: Statistically significant enrichment of rare (minor allele frequency < 1 x 10-5) probably damaging SPTAN1 variants was identified in families with hereditary ataxia (HA) or hereditary spastic paraplegia (HSP) (12/1142 cases vs 52/23,847 controls, p = 2.8 x 10-5). We identified 31 individuals carrying SPTAN1 heterozygous variants or deletions. A total of 10 patients presented with pure or complex HSP/HA. The remaining 21 patients had developmental delay and seizures. Irregular alpha II-spectrin aggregation was noted in fibroblasts derived from 2 patients with p.(Arg19Trp) and p.(Glu2207del) variants.Conclusion: We found that SPTAN1 is a genetic cause of neurodevelopmental disorder, which we classified into 3 distinct subgroups. The first comprises developmental epileptic encepha-lopathy. The second group exhibits milder phenotypes of developmental delay with or without seizures. The final group accounts for patients with pure or complex HSP/HA.(c) 2022 The Authors. Published by Elsevier Inc. on behalf of American College of Medical Genetics and Genomics. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

BackgroundPatients, families, the healthcare system, and society as a whole are all significantly impacted by rare diseases (RDs). According to various classifications, there are currently up to 9,000 different rare diseases that have been recognized, and new diseases are discovered every month. Although very few people are affected by each uncommon disease individually, millions of people are thought to be impacted globally when all these conditions are considered. Therefore, RDs represent an important public health concern. Although crucial for clinical care, early and correct diagnosis is still difficult to achieve in many nations, especially those with low and middle incomes. Consequently, a sizeable amount of the overall burden of RD is attributable to undiagnosed RD (URD). Existing barriers and policy aspects impacting the care of patients with RD and URD remain to be investigated.MethodsTo identify unmet needs and opportunities for patients with URD, the Developing Nations Working Group of the Undiagnosed Diseases Network International (DNWG-UDNI) conducted a survey among its members, who were from 20 different nations. The survey used a mix of multiple choice and dedicated open questions covering a variety of topics. To explore reported needs and analyze them in relation to national healthcare economical aspects, publicly available data on (a) World Bank ranking; (b) Current health expenditure per capita; (c) GDP per capita; (d) Domestic general government health expenditure (% of GDP); and (e) Life expectancy at birth, total (years) were incorporated in our study.ResultsThis study provides an in-depth evaluation of the unmet needs for 20 countries: low-income (3), middle-income (10), and high-income (7). When analyzing reported unmet needs, almost all countries (N = 19) indicated that major barriers still exist when attempting to improve the care of patients with UR and/or URD; most countries report unmet needs related to the availability of specialized care and dedicated facilities. However, while the countries ranked as low income by the World Bank showed the highest prevalence of referred unmet needs across the different domains, no specific trend appeared when comparing the high, upper, and low-middle income nations. No overt trend was observed when separating countries by current health expenditure per capita, GDP per capita, domestic general government health expenditure (% of GDP) and life expectancy at birth, total (years). Conversely, both the GDP and domestic general government health expenditure for each country impacted the presence of ongoing research.ConclusionWe found that policy characteristics varied greatly with the type of health system and country. No overall pattern in terms of referral for unmet needs when separating countries by main economic or health indicators were observed. Our findings highlight the importance of identifying actionable points (e.g., implemented orphan drug acts or registries where not available) in order to improve the care and diagnosis of RDs and URDs on a global scale.

Down syndrome (DS) is a leading human genomic abnormality resulting from the trisomy of chromosome 21. The genomic base of the aneuploidy behind this disease is complex, and this complexity poses formidable challenges to understanding the underlying molecular basis. In the spectrum of the classic DS risk factor associations the role of nutrients, vitamins, and in general, the foodborne associated background as part of the events leading ultimately to chromosome nondisjunction has long been recognized as a well-established clinical association. The integrity of the microbiome is a basic condition in these events, and the dysbiosis may be associated with secondary health outcomes, the possible association of DS development with maternal gut microbiota should require more attention. We have hypothesized that different classes of antibiotics might promote or inhibit the proliferation of different microbial taxa and hence, we might find associations between the use of different classes of antibiotics and the prevalence of DS through the modification of the microbiome. As antibiotics are considered major disruptors of the microbiome, it could be hypothesized that the consumption/exposure of certain classes of antibiotics might be associated with the prevalence of DS in European countries (N=30). Utilizing three different statistical methods, comparisons have been made between the average yearly antibiotic consumption (1997-2020) and the prevalence of people living with DS estimated for 2019 as a percentage of the population in European countries. We have found strong statistical correlations between the consumption of tetracycline (J01A) and the narrow-spectrum, beta-lactamase-resistant penicillin (J01CF) and the prevalence of DS.

IntroductionRare diseases (RD) are a health priority worldwide, overall affecting hundreds of millions of people globally. Early and accurate diagnosis is essential to support clinical care but remains challenging in many countries, especially the low- and medium-income ones. Hence, undiagnosed RD (URD) account for a significant portion of the overall RD burden.MethodsIn October 2020, the Developing Nations Working Group of the Undiagnosed Diseases Network International (DNWG-UDNI) launched a survey among its members, belonging to 20 countries across all continents, to map unmet needs and opportunities for patients with URD. The survey was based on questions with open answers and included eight different domains. Conflicting interpretations were resolved in contact with the partners involved.ResultsAll members responded to the survey. The results indicated that the scientific and medical centers make substantial efforts to respond to the unmet needs of patients. In most countries, there is a high awareness of RD issues. Scarcity of resources was highlighted as a major problem, leading to reduced availability of diagnostic expertise and research. Serious equity in accessibility to services were highlighted both within and between participating countries. Regulatory problems, including securing informed consent, difficulties in sending DNA to foreign laboratories, protection of intellectual property, and conflicts of interest on the part of service providers, remain issues of concern. Finally, most respondents stressed the need to strengthen international cooperation in terms of data sharing, clinical research, and diagnostic expertise for URD patients in low and medium income countries.DiscussionThe survey highlighted that many countries experienced a discrepancy between the growing expertise and scientific value, the level of awareness and commitment on the part of relevant parties, and funding bodies. Country-tailored public health actions, including general syllabus of medical schools and of the education of other health professionals, are needed to reduce such gaps.

[This corrects the article DOI: 10.1515/medgen-2022-2116.].

Background and Objectives Neurofilament light (NfL) appears to be a promising fluid biomarker in repeat-expansion spinocerebellar ataxias (SCAs), with piloting studies in mixed SCA cohorts suggesting that NfL might be increased at the ataxic stage of SCA type 1 (SCA1). We here hypothesized that NfL is increased not only at the ataxic stage of SCA1, but also at its (likely most treatment-relevant) preataxic stage. Methods We assessed serum NfL (sNfL) and CSF NfL (cNfL) levels in both preataxic and ataxic SCA1, leveraging a multicentric cohort recruited at 6 European university centers, and clinical follow-up data, including actually observed (rather than only predicted) conversion to the ataxic stage. Levels of sNfL and cNfL were assessed by single-molecule array and ELISA technique, respectively. Results Forty individuals with SCA1 (23 preataxic, 17 ataxic) and 89 controls were enrolled, including 11 preataxic individuals converting to the ataxic stage. sNfL levels were increased at the preataxic (median 15.5 pg/mL [interquartile range 10.5–21.1 pg/mL]) and ataxic stage (31.6 pg/mL [26.2–37.7 pg/mL]) compared to controls (6.0 pg/mL [4.7–8.6 pg/mL]), yielding high age-corrected effect sizes (preataxic: r = 0.62, ataxic: r = 0.63). sNfL increases were paralleled by increases of cNfL at both the preataxic and ataxic stage. In preataxic individuals, sNfL levels increased with proximity to predicted ataxia onset, with significant sNfL elevations already 5 years before onset, and confirmed in preataxic individuals with actually observed ataxia onset. sNfL increases were detected already in preataxic individuals with SCA1 without volumetric atrophy of cerebellum or pons, suggesting that sNfL might be more sensitive to early preataxic neurodegeneration than the currently known most change-sensitive regions in volumetric MRI. Using longitudinal sNfL measurements, we estimated sample sizes for clinical trials with the reduction of sNfL as the endpoint. Discussion sNfL levels might provide easily accessible peripheral biomarkers in both preataxic and ataxic SCA1, allowing stratification of preataxic individuals regarding proximity to onset, early detection of neurodegeneration even before volumetric MRI alterations, and potentially capture of treatment response in clinical trials. Trial Registration Information ClinicalTrials.gov Identifier: NCT01037777. Classification of Evidence This study provides Class III evidence that NfL levels are increased in both ataxic and preataxic SCA1 and are associated with ataxia onset.