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Simple Summary: Pathogenic variants in the PALB2 gene significantly increase the risk of developing breast, ovarian, and pancreatic cancers. However, the prevalence of these mutations in East Asian populations, particularly Koreans, has not been well studied. This research aims to estimate the prevalence of PALB2 variants in these populations by analyzing large-scale genomic databases. Understanding the frequency of PALB2 variants can help in identifying individuals at higher risk for these cancers and guide the development of targeted screening and prevention strategies. The findings from this study provide valuable reference data that can enhance genetic counseling and improve cancer risk management in East Asian populations, ultimately contributing to better health outcomes in these communities. PALB2 is a tumor suppressor gene. Heterozygous germline pathogenic variants of PALB2 significantly increase the lifetime risk of breast cancer and moderately increase the risk of ovarian and pancreatic cancers. This study analyzed the estimated prevalence of PALB2 variants globally, focusing on East Asian and Korean populations, where limited data were previously available. We examined 125,748 exomes from the Genome Aggregation Database (gnomAD), including 9197 East Asians, and additional data from 5305 individuals in the Korean Variant Archive and 1722 in the Korean Reference Genome Database. All PALB2 variants were interpreted according to guidelines from the American College of Medical Genetics and Genomics and the Clinical Genome Resource. The global prevalence of PALB2 variants was 0.18%, with the highest prevalence in Finnish populations (0.41%) and the lowest in Ashkenazi Jewish populations (0.04%). East Asians had a prevalence of 0.09%. By combining data from Korean genome databases and gnomAD totaling 8936 individuals, the overall prevalence of PALB2 variants in the Korean population was determined to be 0.13%. This study is the first comprehensive investigation of PALB2 variant prevalence in East Asians and Koreans using gnomAD and Korean genome databases. These findings provide essential reference data for future research and highlight the importance of region-specific genetic studies that will inform genetic counseling and hereditary cancer risk management. [ABSTRACT FROM AUTHOR]

BackgroundMutations in the fused in sarcoma (FUS) gene have been linked to amyotrophic lateral sclerosis (ALS). ALS patients with FUS mutations exhibit neuronal cytoplasmic mislocalization of the mutant FUS protein. ALS patients' fibroblasts or induced pluripotent stem cell (iPSC)-derived neurons have been developed as models for understanding ALS-associated FUS (ALS-FUS) pathology; however, pathological neuronal signatures are not sufficiently present in the fibroblasts of patients, whereas the generation of iPSC-derived neurons from ALS patients requires relatively intricate procedures.ResultsHere, we report the generation of disease-specific induced neurons (iNeurons) from the fibroblasts of patients who carry three different FUS mutations that were recently identified by direct sequencing and multi-gene panel analysis. The mutations are located at the C-terminal nuclear localization signal (NLS) region of the protein (p.G504Wfs*12, p.R495*, p.Q519E): two de novo mutations in sporadic ALS and one in familial ALS case. Aberrant cytoplasmic mislocalization with nuclear clearance was detected in all patient-derived iNeurons, and oxidative stress further induced the accumulation of cytoplasmic FUS in cytoplasmic granules, thereby recapitulating neuronal pathological features identified in mutant FUS (p.G504Wfs*12)-autopsied ALS patient. Importantly, such FUS pathological hallmarks of the patient with the p.Q519E mutation were only detected in patient-derived iNeurons, which contrasts to predominant FUS (p.Q519E) in the nucleus of both the transfected cells and patient-derived fibroblasts.ConclusionsThus, iNeurons may provide a more reliable model for investigating FUS mutations with disrupted NLS for understanding FUS-associated proteinopathies in ALS.

Krabbe disease (KD) is an autosomal recessive neurodegenerative disorder caused by defective β-galactosylceramidase (GALC), a lysosomal enzyme responsible for cleavage of several key substrates including psychosine. Accumulation of psychosine to the cytotoxic levels in KD patients is thought to cause dysfunctions in myelinating glial cells based on a comprehensive study of demyelination in KD. However, recent evidence suggests myelin-independent neuronal death in the murine model of KD, thus indicating defective GALC in neurons as an autonomous mechanism for neuronal cell death in KD. These observations prompted us to generate induced neurons (iNeurons) from two adult-onset KD patients carrying compound heterozygous mutations (p.[K563*];[L634S]) and (p.[N228_S232delinsTP];[G286D]) to determine the direct contribution of autonomous neuronal toxicity to KD. Here we report that directly converted KD iNeurons showed not only diminished GALC activity and increased psychosine levels, as expected, but also neurite fragmentation and abnormal neuritic branching. The lysosomal-associated membrane proteins 1 (LAMP1) was expressed at higher levels than controls, LAMP1-positive vesicles were significantly enlarged and fragmented, and mitochondrial morphology and its function were altered in KD iNeurons. Strikingly, we demonstrated that psychosine was sufficient to induce neurite defects, mitochondrial fragmentation, and lysosomal alterations in iNeurons derived in healthy individuals, thus establishing the causal effect of the cytotoxic GALC substrate in KD and the autonomous neuronal toxicity in KD pathology.