Ebba Lohmann’s research while affiliated with University of Tübingen and other places

Dystonia is one of the most prevalent movement disorders, characterized by significant clinical and etiological heterogeneity. Despite considerable heritability (~25%) and the identification of several disease-linked genes, the etiology in most patients remains elusive. Moreover, understanding the correlations between clinical manifestation and genetic variants has become increasingly complex. To comprehensively unravel dystonia's genetic spectrum, we performed exome sequencing on 1,924 dystonia patients [40.3% male, 92.9% White, 93.2% isolated dystonia, median age at onset (AAO) 33 years], including 1,895 index patients, who were previously genetically unsolved. The sample was mainly based on two dystonia registries (DysTract and the Dystonia Coalition). Further, 72 additional patients of Asian ethnicity, mainly from Malaysia, were also included. We prioritized patients with negative genetic prescreening, early AAO, positive family history, and multisite involvement of dystonia. Rare variants in genes previously linked to dystonia (n=405) were examined. Variants were confirmed via Sanger sequencing, and segregation analysis was performed when possible. We identified 137 distinct likely pathogenic or pathogenic variants (according to ACMG criteria) across 51 genes in 163/1,924 patients [42.9% male, 85.9% White, 68.7% isolated dystonia, median AAO 19 years]. This included 153/1,898 index patients, resulting in a diagnostic yield of 8.1%. Notably, 77/137 (56.2%) of these variants were novel, with recurrent variants in EIF2AK2, VPS16, KCNMA1, and SLC2A1, and novel variant types such as two splice site variants in KMT2B, supported by functional evidence. Additionally, 321 index patients (16.9%) harbored variants of uncertain significance in 102 genes. The most frequently implicated genes included VPS16, THAP1, GCH1, SGCE, GNAL, and KMT2B. Presumably pathogenic variants in less well-established dystonia genes were also found, including KCNMA1, KIF1A, and ZMYND11. At least six variants (in ADCY5, GNB1, IR2BPL, KCNN2, KMT2B, and VPS16) occurred de novo, supporting pathogenicity. ROC curve analysis indicated that AAO and the presence of generalized dystonia were the strongest predictors of a genetic diagnosis, with diagnostic yields of 28.6% in patients with generalized dystonia and 20.4% in those with AAO < 30 years. This study provides a comprehensive examination of the genetic landscape of dystonia, revealing valuable insights into the frequency of dystonia-linked genes and their associated phenotypes. It underscores the utility of exome sequencing in establishing diagnoses within this heterogeneous condition. Despite prescreening, presumably pathogenic variants were identified in almost 10% of patients. Our findings reaffirm several dystonia candidate genes and expand the phenotypic spectrum of some of these genes to include prominent, sometimes isolated dystonia.

Background Despite considerable heritability, previous smaller genome‐wide association studies (GWASs) have not identified any robust genetic risk factors for isolated dystonia. Objective The objective of this study was to perform a large‐scale GWAS in a well‐characterized, multicenter sample of >6000 individuals to identify genetic risk factors for isolated dystonia. Methods Array‐based GWASs were performed on autosomes for 4303 dystonia participants and 2362 healthy control subjects of European ancestry with subgroup analysis based on age at onset, affected body regions, and a newly developed clinical score. Another 736 individuals were used for validation. Results This GWAS identified no common genome‐wide significant loci that could be replicated despite sufficient power to detect meaningful effects. Power analyses imply that the effects of individual variants are likely very small. Conclusions Moderate single‐nucleotide polymorphism–based heritability indicates that common variants do not contribute to isolated dystonia in this cohort. Sequence‐based GWASs (eg, by whole‐genome sequencing) might help to better understand the genetic basis. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Background Pathogenic heterozygous mutations in the progranulin gene (GRN) are a key cause of frontotemporal dementia (FTD), leading to significantly reduced biofluid concentrations of the progranulin protein (PGRN). This has led to a number of ongoing therapeutic trials aiming to treat this form of FTD by increasing PGRN levels in mutation carriers. However, we currently lack a complete understanding of factors that affect PGRN levels and potential variation in measurement methods. Here, we aimed to address this gap in knowledge by systematically reviewing published literature on biofluid PGRN concentrations. Methods Published data including biofluid PGRN concentration, age, sex, diagnosis and GRN mutation were collected for 7071 individuals from 75 publications. The majority of analyses (72%) had focused on plasma PGRN concentrations, with many of these (56%) measured with a single assay type (Adipogen) and so the influence of mutation type, age at onset, sex, and diagnosis were investigated in this subset of the data. Results We established a plasma PGRN concentration cut-off between pathogenic mutation carriers and non-carriers of 74.8 ng/mL using the Adipogen assay based on 3301 individuals, with a CSF concentration cut-off of 3.43 ng/mL. Plasma PGRN concentration varied by GRN mutation type as well as by clinical diagnosis in those without a GRN mutation. Plasma PGRN concentration was significantly higher in women than men in GRN mutation carriers (p = 0.007) with a trend in non-carriers (p = 0.062), and there was a significant but weak positive correlation with age in both GRN mutation carriers and non-carriers. No significant association was seen with weight or with TMEM106B rs1990622 genotype. However, higher plasma PGRN levels were seen in those with the GRN rs5848 CC genotype in both GRN mutation carriers and non-carriers. Conclusions These results further support the usefulness of PGRN concentration for the identification of the large majority of pathogenic mutations in the GRN gene. Furthermore, these results highlight the importance of considering additional factors, such as mutation type, sex and age when interpreting PGRN concentrations. This will be particularly important as we enter the era of trials for progranulin-associated FTD.

Background Dystonia is one of the most common movement disorders. To date, the genetic causes of dystonia in populations of European descent have been extensively studied. However, other populations, particularly those from the Middle East, have not been adequately studied. The purpose of this study is to discover the genetic basis of dystonia in a clinically and genetically well-characterised dystonia cohort from Turkey, which harbours poorly studied populations. Methods Exome sequencing analysis was performed in 42 Turkish dystonia families. Using co-expression network (CEN) analysis, identified candidate genes were interrogated for the networks including known dystonia-associated genes and genes further associated with the protein-protein interaction, animal model-based characteristics and clinical findings. Results We identified potentially disease-causing variants in the established dystonia genes ( PRKRA, SGCE, KMT2B, SLC2A1, GCH1, THAP1, HPCA, TSPOAP1, AOPEP ; n=11 families (26%)), in the uncommon forms of dystonia-associated genes ( PCCB, CACNA1A, ALDH5A1, PRKN ; n=4 families (10%)) and in the candidate genes prioritised based on the pathogenicity of the variants and CEN-based analyses (n=11 families (21%)). The diagnostic yield was found to be 36%. Several pathways and gene ontologies implicated in immune system, transcription, metabolic pathways, endosomal-lysosomal and neurodevelopmental mechanisms were over-represented in our CEN analysis. Conclusions Here, using a structured approach, we have characterised a clinically and genetically well-defined dystonia cohort from Turkey, where dystonia has not been widely studied, and provided an uncovered genetic basis, which will facilitate diagnostic dystonia research.

Background Pathogenic variants in several genes have been linked to genetic forms of isolated or combined dystonia. The phenotypic and genetic spectrum and the frequency of pathogenic variants in these genes have not yet been fully elucidated, neither in patients with dystonia nor with other, sometimes co‐occurring movement disorders such as Parkinson's disease (PD). Objectives To screen >2000 patients with dystonia or PD for rare variants in known dystonia‐causing genes. Methods We screened 1207 dystonia patients from Germany (DysTract consortium), Spain, and South Korea, and 1036 PD patients from Germany for pathogenic variants using a next‐generation sequencing gene panel. The impact on DNA methylation of KMT2B variants was evaluated by analyzing the gene's characteristic episignature. Results We identified 171 carriers (109 with dystonia [9.0%]; 62 with PD [6.0%]) of 131 rare variants (minor allele frequency <0.005). A total of 52 patients (48 dystonia [4.0%]; four PD [0.4%, all with GCH1 variants]) carried 33 different (likely) pathogenic variants, of which 17 were not previously reported. Pathogenic biallelic variants in PRKRA were not found. Episignature analysis of 48 KMT2B variants revealed that only two of these should be considered (likely) pathogenic. Conclusion This study confirms pathogenic variants in GCH1 , GNAL , KMT2B , SGCE , THAP1 , and TOR1A as relevant causes in dystonia and expands the mutational spectrum. Of note, likely pathogenic variants only in GCH1 were also found among PD patients. For DYT‐KMT2B, the recently described episignature served as a reliable readout to determine the functional effect of newly identified variants. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Objective: Estrogen receptor 1 (ESR1) polymorphisms are associated with Alzheimer's disease (AD) and polymorphisms in the first intronic region of the gene are known to affect ESR1 mRNA transcription. The first intronic region of the ESR1 contains two polymorphisms that have received the most attention: PvuII rs2234693 (NM 000125.3: c.453-397T>C) and XbaI rs9340799 (NM 000125.3: c.453-351A>G). Both polymorphisms have been shown to be associated with AD, but consistent findings across populations have not been established. This study aimed to determine whether ESR1 PvuII and XbaI polymorphisms are associated with the disease in a cohort of Turkish AD patients. Whether PvuII and XbaI polymorphisms affect disease susceptibility by influencing ESR1 mRNA expression was also examined. Materials and Methods: Genotyping was performed in 424 patients with AD (mean age: 64.5 +- 11.1 yrs) and 302 controls (mean age: 56.4 +- 13.0 yrs). The polymerase chain reaction (PCR) and restriction enzyme digestion methods were used to determine the prevalence of the ESR1 PvuII and XbaI polymorphisms. The ESR1 mRNA expression was analyzed in the peripheral blood cells of 85 patients and 53 age-matched controls using quantitative real-time PCR. Results: No significant difference in genotype and allele frequencies of ESR1 PvuII and XbaI polymorphisms between the patients and controls was found. However, the frequencies of the PvuII C and XbaI G alleles were significantly higher in the patients with the apolipoprotein-E (APOE) ε4 allele. The ESR1 mRNA levels were significantly lower in the patients with AD compared with the controls (P = 0.001). The XbaI A allele was significantly associated with lower ESR1 mRNA levels (P = 0.044) and this association remained significant even after adjusting for confounders such as age, gender and APOE ε4 carrier status (P = 0.035). Conclusion: This study demonstrated that the distribution of PvuII and XbaI alleles is associated with the APOE ε4 allele. The XbaI polymorphism may be associated with a higher risk of AD by altering ESR1 mRNA levels.

Objectives Estrogen receptor 1 (ESR1) gene polymorphisms are associated with Alzheimer's disease (AD) and ESR1 mRNA transcription is affected by polymorphisms in the first intronic region of the gene. ESR1 PvuII rs2234693 (NM 000125.3:c.453-397T > C) and XbaI rs9340799 (NM 000125.3:c.453-351A > G) polymorphisms have been shown to be associated with AD. In this study, we sought to determine the association of PvuII and XbaI polymorphisms with AD. We also examined whether PvuII and XbaI polymorphisms affect disease susceptibility by influencing ESR1 mRNA expression. Methods Genotyping was performed in 424 AD patients and 302 controls. The polymerase chain reaction and restriction enzyme digestion was used to determine the prevalence of the ESR1 polymorphisms. ESR1 mRNA expression was analyzed in blood cells of 85 patients and 53 age-matched controls by quantitative real-time polymerase chain reaction. Results Our results showed no significant difference in genotype and allele frequencies of ESR1 PvuII and XbaI polymorphisms between patients and controls but frequencies of the PvuII C and XbaI G alleles were significantly higher in patients with the APOE ε4 allele. ESR1 mRNA levels were significantly lower in AD patients compared with controls (p = 0.001). XbaI A allele is significantly associated with lower ESR1 mRNA levels (p = 0.044) and this association remained significant after adjusting for age, gender and APOE ε4 carrier status (p = 0.035). Conclusion Our study showed that the distribution of PvuII and XbaI alleles were associated with the APOE ε4 allele. The XbaI polymorphism may be associated with a higher risk of AD by altering ESR1 mRNA levels.

Valosin-containing protein (VCP) mutations are causative for multisystem proteinopathy, a disease characterized by variable phenotypes including inclusion body myopathy, Paget's disease of bone, and frontotemporal dementia. More recent reports identified VCP variants as the cause of other neurodegenerative diseases, such as Parkinson's disease and vacuolar tauopathy. We screened a Turkish dementia cohort for VCP variants in order to assess their role as the cause of disease in this population. One hundred and forty six Turkish dementia patients were examined clinically and were analyzed for VCP coding variants using whole-exome sequencing. Familial samples were collected and analyzed in order to test for segregation of candidate variants. We identified a heterozygous missense VCP p.Ile216Met variant segregating with disease in a family where the proband was diagnosed with prodromal dementia with Lewy bodies. Our report potentially extends the spectrum of phenotypes attributed to VCP mutations to include prodromal dementia with Lewy bodies.