Germline BRCA2 pathogenic variants in pediatric ganglioglioma: Case report and review of the literature.

BACKGROUND: BRCA1 and BRCA2 are tumor suppressor genes associated with increased risk of breast and ovarian cancer in adulthood. Patients with germline pathogenic variants in these genes have also been reported to develop brain tumors, although it is unclear whether these syndromes are associated with significant increased risk of brain tumor formation. RESULTS: Here, we report a case of a child with germline BRCA2 pathogenic variant presenting with a symptomatic ganglioglioma. To our knowledge, this is the first such patient to be reported. We discuss prior cases of brain tumors in BRCA1/2 patients and evidence for a potential role for BRCA1/2 pathogenic variants in brain tumor formation. CONCLUSION: BRCA2 germline variants may increase the risk of developing some types of pediatric brain tumors, but further study is needed to determine its effect on low-grade glioma formation.

Neuropathological Applications of Microscopy with Ultraviolet Surface Excitation (MUSE): A Concordance Study of Human Primary and Metastatic Brain Tumors.

Whereas traditional histology and light microscopy require multiple steps of formalin fixation, paraffin embedding, and sectioning to generate images for pathologic diagnosis, Microscopy using Ultraviolet Surface Excitation (MUSE) operates through UV excitation on the cut surface of tissue, generating images of high resolution without the need to fix or section tissue and allowing for potential use for downstream molecular tests. Here, we present the first study of the use and suitability of MUSE microscopy for neuropathological samples. MUSE images were generated from surgical biopsy samples of primary and metastatic brain tumor biopsy samples (n = 27), and blinded assessments of diagnoses, tumor grades, and cellular features were compared to corresponding hematoxylin and eosin (H&E) images. A set of MUSE-treated samples subsequently underwent exome and targeted sequencing, and quality metrics were compared to those from fresh frozen specimens. Diagnostic accuracy was relatively high, and DNA and RNA integrity appeared to be preserved for this cohort. This suggests that MUSE may be a reliable method of generating high-quality diagnostic-grade histologic images for neuropathology on a rapid and sample-sparing basis and for subsequent molecular analysis of DNA and RNA.

A Retrospective Genomic Landscape of 661 Young Adult Glioblastomas Diagnosed Using 2016 WHO Guidelines for Central Nervous System Tumors.

The authors present a cohort of 661 young adult glioblastomas diagnosed using 2016 WHO World Health Organization Classification of Tumors of the Central Nervous System, utilizing comprehensive genomic profiling (CGP) to explore their genomic landscape and assess their relationship to currently defined disease entities. This analysis explored variants with evidence of pathogenic function, common copy number variants (CNVs), and several novel fusion events not described in literature. Tumor mutational burden (TMB) mutational signatures, anatomic location, and tumor recurrence are further explored. Using data collected from CGP, unsupervised machine-learning techniques were leveraged to identify 10 genomic classes in previously assigned young adult glioblastomas. The authors relate these molecular classes to current World Health Organization guidelines and reference current literature to give therapeutic and prognostic descriptions where possible.

POU2AF3-rearranged sarcomas: A novel tumor defined by fusions of EWSR1 or FUS to a gene formerly designated COLCA2.

Gene fusions involving EWSR1 or FUS as the 5' partner have been reported in a diverse array of sarcomas. Here, we characterize the histopathology and genomics of six tumors harboring a gene fusion between EWSR1 or FUS and POU2AF3, an understudied, putative colorectal cancer predisposition gene. Striking morphologic features reminiscent of synovial sarcoma were observed including a biphasic appearance with variable fusiform to epithelioid cytomorphology and staghorn-type vasculature. RNA sequencing demonstrated variable breakpoints in EWSR1/FUS along with similar breakpoints in POU2AF3 that encompassed a 3' portion of this gene. For cases in which additional information was available, the behavior of these neoplasms was aggressive with local spread and/or distant metastases. Although further studies are needed to confirm the functional significance of our findings, POU2AF3 fusions to EWSR1 or FUS may define a novel type of POU2AF3-rearranged sarcomas with aggressive, malignant behavior.

Lessons learned from evolving frameworks in adult glioblastoma.

Glioblastoma (GBM) is the most common and aggressive malignant adult brain tumor. Significant effort has been directed to achieve a molecular subtyping of GBM to impact treatment. The discovery of new unique molecular alterations has resulted in a more effective classification of tumors and has opened the door to subtype-specific therapeutic targets. Morphologically identical GBM may have different genetic, epigenetic, and transcriptomic alterations and therefore different progression trajectories and response to treatments. With a transition to molecularly guided diagnosis, there is now a potential to personalize and successfully manage this tumor type to improve outcomes. The steps to achieve subtype-specific molecular signatures can be extrapolated to other neuroproliferative as well as neurodegenerative disorders.

Genomic Profiling Reveals Differences in Primary Central Nervous System Lymphoma and Large B-Cell Lymphoma, With Subtyping Suggesting Sensitivity to BTK Inhibition.

BACKGROUND: B-cell primary central nervous system (CNS) lymphoma (PCL) is diffuse large B-cell lymphoma (DLBCL) confined to the CNS. Less than 50% of patients with PCL achieve complete remission with current therapies. We describe the findings from comprehensive genomic profiling (CGP) of a cohort of 69 patients with PCL, 36 cases of secondary CNS lymphoma (SCL), and 969 cases of DLBCL to highlight their differences and characterize the PCL cohort. In addition, we highlight the differences in frequency of germinal center B-cell like (GCB) and non-GCB subtypes and molecular subtypes, particularly MCD and EZH subtypes, between PCL and DLBCL. MATERIALS AND METHODS: Sixty-nine cases of B-cell PCL, 36 cases of secondary CNS lymphoma (SCL), and 969 cases of DLBCL were evaluated by CGP of 405 genes via DNAseq and 265 genes via RNAseq for fusions (FoundationOne Heme). Tumor mutational burden (TMB) was calculated from 1.23 Mb of sequenced DNA. RESULTS: Genomic alterations with significant differences between PCL and DLBCL included MYD88, ETV6, PIM1, PRDM1, CXCR4, TP53, and CREBBP, while only MYD88 was significantly different between SCL and DLBCL. PCL cases were significantly enriched for the MCD molecular subtypes, which have an excellent response to BTKi. We report a patient with a durable complete response to BTKi consistent with their genomic profile. EBV status, CD274 amplification, and TMB status suggest that 38% of PCL patients may benefit from ICPI; however further study is warranted. CONCLUSION: CGP of PCLs reveals biomarkers, genomic alterations, and molecular classifications predictive of BTKi efficacy and potential ICPI efficacy. Given the limitations of standard of care for PCL, CGP is critical to identify potential therapeutic approaches for patients in this rare form of lymphoma.

Hidden treasures: Incidental findings in two cases of chronic subdural hematoma.

Background: Extramedullary hematopoiesis (EMH) and plasmacytomas occurring within the cranium are rare entities. Case Description: We review two cases in which patients presented with subdural hematoma and underwent evacuation. On routine histopathologic examination of their membranes, both patients were subsequently found to have focal EMH, as well as a clonal plasma cell proliferation in one case. Conclusion: EMH is rare and usually found in individuals with profound and chronic anemia. However, this entity may be more common in chronic subdural hematomas. Solitary extraosseous plasmacytoma is exceedingly rare in the cranium, and its presence in chronic subdural hematoma membranes is of uncertain significance. The cytokine milieu that promotes organization of chronic subdural hematomas may play a role in the establishment of both of entities in this location.

Advances in Immunotherapy for the Treatment of Adult Glioblastoma: Overcoming Chemical and Physical Barriers.

Glioblastoma, or glioblastoma multiforme (GBM, WHO Grade IV), is a highly aggressive adult glioma. Despite extensive efforts to improve treatment, the current standard-of-care (SOC) regimen, which consists of maximal resection, radiotherapy, and temozolomide (TMZ), achieves only a 12-15 month survival. The clinical improvements achieved through immunotherapy in several extracranial solid tumors, including non-small-cell lung cancer, melanoma, and non-Hodgkin lymphoma, inspired investigations to pursue various immunotherapeutic interventions in adult glioblastoma patients. Despite some encouraging reports from preclinical and early-stage clinical trials, none of the tested agents have been convincing in Phase III clinical trials. One, but not the only, factor that is accountable for the slow progress is the blood-brain barrier, which prevents most antitumor drugs from reaching the target in appreciable amounts. Herein, we review the current state of immunotherapy in glioblastoma and discuss the significant challenges that prevent advancement. We also provide thoughts on steps that may be taken to remediate these challenges, including the application of ultrasound technologies.

Molecular analysis of endometrial serous carcinoma reveals distinct clinicopathologic and genomic subgroups.

OBJECTIVES: Endometrial serous carcinoma (EMSC) is an aggressive variant of uterine cancer with limited therapeutic options. We sought to define distinct clinicopathologic and genomic EMSC subgroups. METHODS: We retrospectively analyzed 2159 EMSC and 2346 endometrioid-type endometrial carcinomas (EEC) tissue specimens that had undergone comprehensive genomic profiling (CGP) via the FoundationOne CDx assay during routine clinical care. High tumor mutational burden (TMB) was defined as ≥10mut/Mb using the FDA-approved CDx cutoff for pembrolizumab. Microsatellite instability (MSI) was determined on 95 loci. Evidence of homologous recombination deficiency (HRD) was determined via genomic loss of heterozygosity (gLOH), a validated HRD detection method for predicting PARP inhibitor effectiveness in ovarian carcinoma. High gLOH was defined as ≥16%. RESULTS: A genomic analysis of 2159 EMSCs revealed a predominance of TP53 mutations, microsatellite stability, low tumor mutational burden (TMB), and recurrent alterations of PIK3CA, PPP2R1A, ERBB2, CCNE1, FBXW7 and MYC. Evidence of HRD via high gLOH was identified in 22% of EMSCs. BRCA1 and BRCA2 alterations, as well as unique SET (solid, pseudo-endometrioid, and transitional cell-like) variant morphology, were enriched in HRD-EMSC. There was an increased frequency of CCNE1 amplification, a lower prevalence of PIK3CA and PPP2R1A alterations, and no differences in HRD, MSI or TMB biomarker frequencies in patients of predicted African ancestry. EMSC exhibited distinct gene mutation frequencies and MSI, TMB and gLOH biomarker signatures compared to a cohort 2346 EEC. CONCLUSIONS: Molecularly defined subgroups provide a framework to test the susceptibility of EMSC to targeted therapies in specific genetic settings (e.g. HRD, PIK3CA, PPP2R1A, ERBB2, MYC, CCNE1).

Extracellular GAPDH Promotes Alzheimer Disease Progression by Enhancing Amyloid-ß Aggregation and Cytotoxicity.

Neuronal cell death at late stages of Alzheimer's disease (AD) causes the release of cytosolic proteins. One of the most abundant such proteins, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), forms stable aggregates with extracellular amyloid-ß (Aß). We detect these aggregates in cerebrospinal fluid (CSF) from AD patients at levels directly proportional to the progressive stages of AD. We found that GAPDH forms a covalent bond with Q15 of Aß that is mediated by transglutaminase (tTG). The Q15A substitution weakens the interaction between Aß and GAPDH and reduces Aß-GAPDH cytotoxicity. Lentivirus-driven GAPDH overexpression in two AD animal models increased the level of apoptosis of hippocampal cells, neural degeneration, and cognitive dysfunction. In contrast, in vivo knockdown of GAPDH reversed these pathogenic abnormalities suggesting a pivotal role of GAPDH in Aß-stimulated neurodegeneration. CSF from animals with enhanced GAPDH expression demonstrates increased cytotoxicity in vitro. Furthermore, RX-624, a specific GAPDH small molecular ligand reduced accumulation of Aß aggregates and reversed memory deficit in AD transgenic mice. These findings argue that extracellular GAPDH compromises Aß clearance and accelerates neurodegeneration, and, thus, is a promising pharmacological target for AD.

Clinicopathological and genomic characterization of BCORL1-driven high-grade endometrial stromal sarcomas.

BCORL1 is a transcriptional corepressor homologous to BCOR. We describe 12 BCORL1-altered uterine sarcomas with striking resemblance to BCOR-altered endometrial stromal sarcoma (BCOR-ESS), including 5 with BCORL1 rearrangements (JAZF1-BCORL1, EP300-BCORL1, or internal BCORL1 rearrangement), 5 with inactivating BCORL1 mutations (T513fs*22, P600fs*1, R945*, R1196*, or R1265fs*4) and 2 with homozygous BCORL1 deletion. The median patient age was 57.5 years (range 33-79). An association with aggressive clinical behavior was identified. Diagnoses assigned prior to genomic testing varied: 7 tumors were previously diagnosed as ESS, 2 as high-grade uterine sarcomas, 2 as myxoid uterine leiomyosarcomas, and 1 as a uterine spindle cell neoplasm consistent with leiomyosarcoma. Tumors harbored frequent gelatinous, mucomyxoid-like appearance by gross examination and unique histology with morphological overlap with BCOR-ESS. Key microscopic features included (1) a spindle cell appearance, most often with at least focal myxoid stroma, (2) variable amounts of hypocellular fibromyxoid spindle areas with lower grade atypia and/or (3) variable amounts of epithelioid areas with higher grade atypia. Specifically, spindle and epithelioid components were present in 100 and 75% of sarcomas, respectively; myxoid stroma was identified in 83%, collagen plaques or fibrosis in 50%, and high-grade nuclear atypia was present in 42%. Like BCOR-ESS, 50% of BCORL1-altered sarcomas exhibited CDK4 amplification or CDKN2A loss. In contrast, 33% harbored NF1 alterations, while 25% had other alterations in the NF2-mTOR pathway, expanding potential therapeutic targets. In conclusion, inactivating BCORL1 genomic alterations may define a distinct subset of high-grade endometrial stromal sarcomas with biological overlap with BCOR-ESS, both of which may mimic myxoid leiomyosarcomas.

Clinicopathologic and Genomic Landscape of Breast Carcinoma Brain Metastases.

BACKGROUND: Among patients with breast carcinoma who have metastatic disease, 15%-30% will eventually develop brain metastases. We examined the genomic landscape of a large cohort of patients with breast carcinoma brain metastases (BCBMs) and compared it with a cohort of patients with primary breast carcinomas (BCs). MATERIAL AND METHODS: We retrospectively analyzed 733 BCBMs tested with comprehensive genomic profiling (CGP) and compared them with 10,772 primary breast carcinomas (not-paired) specimens. For a subset of 16 triple-negative breast carcinoma (TNBC)-brain metastasis samples, programmed death-ligand 1 (PD-L1) immunohistochemistry (IHC) was performed concurrently. RESULTS: A total of 733 consecutive BCBMs were analyzed. Compared with primary BCs, BCBMs were enriched for genomic alterations in TP53 (72.0%, 528/733), ERBB2 (25.6%, 188/733), RAD21 (14.1%, 103/733), NF1 (9.0%, 66/733), BRCA1 (7.8%, 57/733), and ESR1 (6.3%,46/733) (p < .05 for all comparisons). Immune checkpoint inhibitor biomarkers such as high tumor mutational burden (TMB-high; 16.2%, 119/733); high microsatellite instability (1.9%, 14/733); CD274 amplification (3.6%, 27/733); and apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like mutational signature (5.9%, 43/733) were significantly higher in the BCBM cohort compared with the primary BC cohort (p < .05 for all comparisons). When using both CGP and PD-L1 IHC, 37.5% (6/16) of patients with TNBC brain metastasis were eligible for atezolizumab based on PD-L1 IHC, and 18.8% (3/16) were eligible for pembrolizumab based on TMB-high status. CONCLUSION: We found a high prevalence of clinically relevant genomic alterations in patients with BCBM, suggesting that tissue acquisition (surgery) and/or cerebrospinal fluid for CGP in addition to CGP of the primary tumor may be clinically warranted. IMPLICATIONS FOR PRACTICE: This study found a high prevalence of clinically relevant genomic alterations in patients with breast carcinoma brain metastasis (BCBM), suggesting that tissue acquisition (surgery) and/or cerebrospinal fluid for comprehensive genomic profiling (CGP) in addition to CGP of the primary tumor may be clinically warranted. In addition, this study identified higher positive rates for FDA-approved immunotherapy biomarkers detected by CGP in patients with BCBM, opening a possibility of new on-label treatments. Last, this study noted limited correlation between tumor mutational burden and PD-L1 immunohistochemistry (IHC), which shows the importance of testing patients with triple-negative BCBM for immune checkpoint inhibitor eligibility with both PD-L1 IHC and CGP.

Inhibitors of bacterial H2S biogenesis targeting antibiotic resistance and tolerance.

Emergent resistance to all clinical antibiotics calls for the next generation of therapeutics. Here we report an effective antimicrobial strategy targeting the bacterial hydrogen sulfide (H2S)-mediated defense system. We identified cystathionine γ-lyase (CSE) as the primary generator of H2S in two major human pathogens, Staphylococcus aureus and Pseudomonas aeruginosa, and discovered small molecules that inhibit bacterial CSE. These inhibitors potentiate bactericidal antibiotics against both pathogens in vitro and in mouse models of infection. CSE inhibitors also suppress bacterial tolerance, disrupting biofilm formation and substantially reducing the number of persister bacteria that survive antibiotic treatment. Our results establish bacterial H2S as a multifunctional defense factor and CSE as a drug target for versatile antibiotic enhancers.

Exposure to DMSO during infancy alters neurochemistry, social interactions, and brain morphology in long-evans rats.

INTRODUCTION: Dimethyl sulfoxide (DMSO) is a widely used solvent to dissolve hydrophobic substances for clinical uses and experimental in vivo purposes. While usually regarded safe, our prior studies suggest changes to behavior following DMSO exposure. We therefore evaluated the effects of a five-day, short-term exposure to DMSO on postnatal infant rats (P6-10). METHODS: DMSO was intraperitoneally injected for five days at 0.2, 2.0, and 4.0 ml/kg body mass. One cohort of animals was sacrificed 24 hr after DMSO exposure to analyze the neurometabolic changes in four brain regions (cortex, hippocampus, basal ganglia, and cerebellum) by hydrophilic interaction liquid chromatography. A second cohort of animals was used to analyze chronic alterations to behavior and pathological changes to glia and neuronal cells later in life (P21-P40). RESULTS: 164 metabolites, including key regulatory molecules (retinoic acid, orotic acid, adrenic acid, and hypotaurine), were found significantly altered by DMSO exposure in at least one of the brain regions at P11 (p < .05). Behavioral tests showed significant hypoactive behavior and decreased social habits to the 2.0 and 4.0 ml DMSO/kg groups (p < .01). Significant increases in number of microglia and astrocytes at P40 were observed in the 4.0 ml DMSO/kg group (at p < .015.) CONCLUSIONS: Despite short-term exposure at low, putatively nontoxic concentrations, DMSO led to changes in behavior and social preferences, chronic alterations in glial cells, and changes in essential regulatory brain metabolites. The chronic neurological effects of DMSO exposure reported here raise concerns about its neurotoxicity and consequent safety in human medical applications and clinical trials.

Pituitary stalk gangliogliomas: Case report and literature review.

INTRODUCTION: Gangliogliomas rarely occur in the sella or suprasellar region and are almost never seen in the pituitary stalk. Seven cases of gangliogliomas occurring in this region have been reported; only one case involved a tumor within the pituitary stalk. Of the six tumors external to the pituitary stalk, two occurred in the neurohypophysis, one was in the adenohypophysis, the location of one was unspecified, and two extensively invaded the optic chiasm, hypothalamus and brainstem. This is only the second reported case of a pituitary stalk ganglioglioma, and it is unique in its use of an extended endoscopic endonasal approach for biopsy. CASE REPORT: A 51-year old woman presented with an eleven-month history of polydipsia and polyuria leading to the diagnosis of diabetes insipidus. Magnetic Resonance Imaging of the brain revealed contrast-enhanced thickening and anterior bowing of the hypophyseal stalk. An extended endoscopic endonasal approach permitted midline removal of the tuberculum sella, opening of underlying dura, and exposure of the pituitary stalk. A firm, white, 4 mm diameter mass, integral to the right side of the enlarged pituitary stalk was seen and biopsied. Histopathological analysis was consistent with WHO grade 1 ganglioglioma. The patient tolerated the procedure well and required no endocrinologic treatment other than desmopressin. CONCLUSION: Pituitary stalk gangliogliomas are extremely rare. The diagnosis should be considered in patients with pituitary stalk enlargement. Endoscopic endonasal approach is a safe surgical approach to establish a tissue diagnosis which is essential for pathologic certainty given the wide differential diagnosis of stalk lesions.

Congenital presentation of synchronous Atypical Teratoid Rhabdoid Tumor and Malignant Rhabdoid Tumor of the urinary bladder in a term infant.

Atypical teratoid/rhabdoid tumor (AT/RT) is a rare central nervous system (CNS) tumor diagnosed primarily in infants and usually portends a poor prognosis. Despite being the most common embryonal tumor in children less than 1 year old, diagnosis is difficult to make based on clinical findings or imaging alone. A complete diagnosis of AT/RT requires identification of loss of integrase interactor 1 (INI1) protein or the SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily b, member 1 (SMARCB1) gene, in its most common presentation. Moreover, their presentation with other primary rhabdoid tumors in the body raises significant suspicion for rhabdoid tumor predisposition syndrome (RTPS). We report a case of a one-month-old infant admitted for worsening emesis and failure to thrive, who was later found to have brain and bladder masses on radiologic imaging. Autopsy with subsequent immunoprofile and molecular testing were crucial in establishing the absence of INI1 nuclear expression and possible homozygous deletion of SMARCB1 in the urinary bladder tumor tissue. Sequencing of the peripheral blood demonstrated probable single copy loss at the SMARCB1 locus. The constellation of findings in tumor and peripheral blood sequencing suggested the possibility of germline single copy SMARCB1 loss, followed by somatic loss of the remaining SMARCB1 allele due to copy neutral loss-of-heterozygosity. Such a sequence of genetic events has been described in malignant rhabdoid tumors (MRT). Dedicated germline testing of this patient's family members could yield answers as to whether rhabdoid tumor predisposition syndrome will continue to have implications for the patient's family.

Reciprocal H3.3 gene editing identifies K27M and G34R mechanisms in pediatric glioma including NOTCH signaling.

Histone H3.3 mutations are a hallmark of pediatric gliomas, but their core oncogenic mechanisms are not well-defined. To identify major effectors, we used CRISPR-Cas9 to introduce H3.3K27M and G34R mutations into previously H3.3-wildtype brain cells, while in parallel reverting the mutations in glioma cells back to wildtype. ChIP-seq analysis broadly linked K27M to altered H3K27me3 activity including within super-enhancers, which exhibited perturbed transcriptional function. This was largely independent of H3.3 DNA binding. The K27M and G34R mutations induced several of the same pathways suggesting key shared oncogenic mechanisms including activation of neurogenesis and NOTCH pathway genes. H3.3 mutant gliomas are also particularly sensitive to NOTCH pathway gene knockdown and drug inhibition, reducing their viability in culture. Reciprocal editing of cells generally produced reciprocal effects on tumorgenicity in xenograft assays. Overall, our findings define common and distinct K27M and G34R oncogenic mechanisms, including potentially targetable pathways.

Internal Acoustic Canal Stenosis Due to Hyperostosis.

Background Exostoses and osteomas are benign, insidious lesions of the bone involving the internal acoustic canal (IAC). We present two cases of IAC exostoses managed with surgical decompression and review the clinical outcomes of previously reported cases in the literature. Methods A comprehensive search was conducted using PubMed Central, Web of Science Core Collection, and Google Scholar databases to identify previous reports of IAC exostoses and osteomas. A total of 26 reported cases were identified, and patient presenting symptoms, management strategies, and response to surgery was obtained when available. Results Of the 13 patients who underwent surgical decompression, 8 patients had resolution of vertigo symptoms, 10 patients had improvement of tinnitus symptoms, and all patients maintained some level of serviceable hearing. Conclusion IAC exostoses and osteomas are rare lesions that lead to insidious onset of debilitating symptoms from vestibulocochlear nerve dysfunction. Although the role of surgical decompression remains unclear, it appears that patients presenting with vertigo have more favorable response to surgical decompression as compared with those presenting with tinnitus and sensorineural hearing loss.

Parkinsonism Versus Concomitant Parkinson's Disease in Fragile X-Associated Tremor/Ataxia Syndrome.

BACKGROUND: Fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset neurodegenerative disorder associated with premutation alleles (55-200 CGG repeats) of the fragile X mental retardation 1 (FMR1) gene. FXTAS is characterized by the presence of ubiquitin-positive inclusions in neurons and astrocytes and by cerebellar tremor and ataxia. Parkinsonism has been reported in FXTAS, but most patients lack the characteristic rest tremor and severe rigidity seen in idiopathic Parkinson's disease (PD). OBJECTIVE: To describe the frequency of concomitant PD in FXTAS. METHODS: We reviewed the medical record of 40 deceased patients diagnosed with FXTAS and performed a pathology analysis to confirm both FXTAS and PD. RESULTS: Clinical histories indicated that 5 FXTAS patients were diagnosed with idiopathic PD and 2 with atypical parkinsonian syndrome. After pathological examination, we found that 7 patients in the PD clinical diagnosis group had dopaminergic neuronal loss; however, only 2 of 7 presented Lewy bodies (LBs) in the substantia nigra. Therefore, a total of 5% of the 40 cohort patients met the pathologic criteria for the concomitant diagnosis of FXTAS and PD. In addition, 2 patients not clinically diagnosed with PD also had nigral neuronal loss with LBs in substantia nigra. In total 10% of these 40 patients had LBs. CONCLUSION: This report expands our understanding of clinical symptoms and unusual presentations in patients with FXTAS and the concept that the parkinsonism found in FXTAS is sometimes indistinguishable from PD. We propose that FMR1 should be recognized as one of the exceptional genetic causes of parkinsonism with presynaptic dopaminergic loss and LBs.