Katja Lohmann’s research while affiliated with Universitätsklinikum Schleswig - Holstein and other places

LRRK2 -PD represents the most common form of autosomal dominant Parkinson’s disease. We identified the LRRK2 p.L1795F variant in three families and six additional unrelated cases using genetic data from over 50,000 individuals. Carriers with available genotyping data shared a common haplotype. The clinical presentation resembles other LRRK2 -PD forms. Combined with published functional evidence showing strongly enhanced LRRK2 kinase activity, we provide evidence that LRRK2 p.L1795F is pathogenic.

While genetic causes are identified in up to 15% of all Parkinson's disease (PD) patients, the remaining idiopathic PD (iPD) patients are attributed to polygenic risk, environmental and lifestyle factors, and interactions thereof. We applied five advanced polygenic score (PGS) tools to data from 1,762 iPD patients and 4,227 healthy controls of European ancestry, resulting in the development of a novel iPD-PGS with significantly improved discriminative performance compared to existing models with an AUC of 0.680 (95% confidence interval (-CI): [0.665, 0.695]). Validation in independent cohorts confirmed its robustness. Notably, patients with early-onset iPD exhibited markedly high PGS values when compared to late-onset iPD patients and healthy controls, underlining the high polygenetic burden in these individuals. We subsequently applied our novel iPD-PGS to carriers of heterozygous PRKN variants and GBA1 coding risk variants. In both cases, our findings suggest that part of the penetrance in these genetic forms of PD can be explained by the same polygenic alterations as observed mitigating iPD. The discriminative potential was greater for GBA1 than for PRKN (GBA1: AUC=0.639, 95%-CI=[0.590, 0.687], PRKN: AUC=0.594, 95%-CI=[0.501, 0.687]). Our study highlights the potential of advanced PGSs in PD research, particularly for understanding varying penetrance in genetic PD and identifying high-risk individuals.

LRRK2 -related Parkinson’s disease ( LRRK2 -PD) is the most frequent form of monogenic PD worldwide, with important therapeutic opportunities, exemplified by the advancement in LRRK2 kinase inhibition studies/trials. However, many LRRK2 variants, especially those found in underrepresented populations, remain classified as variants of uncertain significance (VUS). Leveraging on Malaysian, Singaporean, and mainland Chinese PD datasets ( n = 4901), we describe 12 Chinese-ancestry patients harboring the LRRK2 p.Arg1067Gln variant, more than doubling the number of previously reported cases (total n = 23, 87% East Asian, mean age of onset: 53.9 years). We determine that this variant is enriched in East Asian PD patients compared to population controls (OR = 8.0, 95% CI: 3.0–20.9), and provide supportive data for its co-segregation with PD, albeit with incomplete penetrance. Utilizing established experimental workflows, this variant showed increased LRRK2 kinase activity, by ~2-fold compared to wildtype and higher than the p.Gly2019Ser variant. Taken together, p.Arg1067Gln should be reclassified from a VUS to pathogenic for causing LRRK2 -PD.

Pathogenic variants in the LRRK2 gene are one of the most commonly identifiable monogenic causes of Parkinson´s disease (PD, PARK-LRRK2). This systematic MDSGene literature review comprehensively summarizes published demographic, clinical, and genetic findings related to LRRK2 variants ( https://www.mdsgene.org/ ). Data on 4660 individuals with 283 different variants were curated. The median age at onset in the PD patients with available information was 56 years, notably, with approximately one-third having PD onset <50 years. Tremor was the most frequently reported initial symptom and more common than reported in other dominantly inherited forms of PD. Of the 211 potentially PD-causing variants, 25 were classified as pathogenic or likely pathogenic, and the remaining 186 (88.2%) were variants of uncertain significance. p.G2019S was the most frequently reported pathogenic variant, followed by p.R1441G and p.R1441C. This systematic review represents the most extensive database on PARK-LRRK2 to date and provides a vital resource to improve precision medicine.

Depending on zygosity and the specific change, different variants in the GBA1 gene can cause Parkinson's disease (PD, PARK-GBA1) with reduced penetrance, act as genetic risk factors for PD or parkinsonism, and/or lead to Gaucher's disease (GD). This MDSGene systematic literature review covers 27,963 patients carrying GBA1 variants from 1082 publications with 794 variants, including 13,342 patients with PD or other forms of parkinsonism. It provides a comprehensive overview of demographic, clinical, and genetic findings from an ethnically diverse sample originating from 82 countries across five continents. The most frequent pathogenic or likely pathogenic variants were "N409S" (aka "N370S"; dominating among Jewish and Whites), and "L483P" (aka "L444P"; dominating among Asians and Hispanics), whereas the most common coding risk variants were "E365K" (E326K), and "T408M" (T369M) (both common among Whites). A novel finding is that early-onset PD patients were predominantly of Asian ethnicity, whereas late-onset PD patients were mainly of White ethnicity. Motor cardinal features were similar between PD patients and other forms of parkinsonism, whereas motor complications and non-motor symptoms were more frequently reported in PD patients carrying "severe" variants than in those with "risk" or "mild" variants. Cognitive decline was reported in most patients after surgical treatment, despite achieving a beneficial motor function response. Most GD patients developing PD harbored the "N409S" variant, were of Ashkenazi Jewish ethnicity, and showed a positive response to chronic levodopa treatment. With this review, we start to fill the gaps regarding genotype-phenotype correlations in GBA1 variant carriers, especially concerning PD. © 2025 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Genetic diagnosis of rare diseases requires accurate identification and interpretation of genomic variants. Clinical and molecular scientists from 37 expert centers across Europe created the Solve-Rare Diseases Consortium (Solve-RD) resource, encompassing clinical, pedigree and genomic rare-disease data (94.5% exomes, 5.5% genomes), and performed systematic reanalysis for 6,447 individuals (3,592 male, 2,855 female) with previously undiagnosed rare diseases from 6,004 families. We established a collaborative, two-level expert review infrastructure that allowed a genetic diagnosis in 506 (8.4%) families. Of 552 disease-causing variants identified, 464 (84.1%) were single-nucleotide variants or short insertions/deletions. These variants were either located in recently published novel disease genes (n = 67), recently reclassified in ClinVar (n = 187) or reclassified by consensus expert decision within Solve-RD (n = 210). Bespoke bioinformatics analyses identified the remaining 15.9% of causative variants (n = 88). Ad hoc expert review, parallel to the systematic reanalysis, diagnosed 249 (4.1%) additional families for an overall diagnostic yield of 12.6%. The infrastructure and collaborative networks set up by Solve-RD can serve as a blueprint for future further scalable international efforts. The resource is open to the global rare-disease community, allowing phenotype, variant and gene queries, as well as genome-wide discoveries.