A rare case of isolated IgG4-related hypophysitis with Rathke's cleft cyst presenting as panhypopituitarism

Summary

We report a rare case of biopsy-proven isolated immunoglobulin G4 (IgG4)-related hypophysitis and Rathke's cleft cyst (RCC) presenting as panhypopituitarism. A 54-year-old Caucasian female presented with symptoms of slurred speech, altered mental status, polyuria and polydipsia and was found to have panhypopituitarism. Brain MRI showed a suprasellar mass with suspected intralesional hemorrhage. She underwent trans-sphenoidal resection due to MRI evidence of compression of the optic chiasm and left optic nerve. Preoperatively, she was started on hydrocortisone, levothyroxine and desmopressin. Histopathology demonstrated a RCC with adjacent lymphoplasmacytic hypophysitis with numerous IgG4-immunoreactive plasma cells. Hydrocortisone was stopped at 10 months after confirming hypothalamic-pituitary-adrenal (HPA)-axis recovery and desmopressin was stopped at 1 year. There was recurrence of a cystic mass at 1 year follow-up. Over 4 years of follow-up, she continued to require levothyroxine, and the mass remained stable in size. In order to begin to understand how this case's unique histopathological presentation influences clinical presentation, pituitary imaging and prognosis, we present an accompanying literature review.

Learning points

Isolated IgG4 hypophysitis and coexisting Rathke's cleft cyst is a rare condition, which presents a diagnostic challenge. Recognizing its characteristic features can assist with early recognition and initiation of therapy to promote optimal outcomes. Further studies investigating the mechanisms promoting co-occurrence of these entities and their effect on prognosis are needed.

Comprehensive BCMA Expression Profiling in Adult Normal Human Brain Suggests a Low Risk of On-target Neurotoxicity in BCMA-targeting Multiple Myeloma Therapy

B-cell maturation antigen (BCMA) is a target for the treatment of multiple myeloma with cytolytic therapies, such as chimeric antigen receptor T-cells or T-cell redirecting antibodies. To better understand the potential for "on-target/off-tumor" toxicity caused by BCMA-targeting cytolytic therapies in the brain, we investigated normal brain BCMA expression. An immunohistochemistry (IHC) assay using the E6D7B commercial monoclonal antibody was applied to 107 formalin-fixed, paraffin-embedded brain samples (cerebrum, basal ganglia, cerebellum, brainstem; 63 unique donors). Although immunoreactivity was observed in a small number of neurons in brain regions including the striatum, thalamus, midbrain, and medulla, this immunoreactivity was considered nonspecific and not reflective of BCMA expression because it was distinct from the membranous and Golgi-like pattern seen in positive control samples, was not replicated when a different IHC antibody (D6 clone) was used, and was not corroborated by in situ hybridization data. Analysis of RNA-sequencing data from 478 donors in the GTEx and Allen BrainSpan databases demonstrated low levels of BCMA RNA expression in the striatum of young donors with levels becoming negligible beyond 30 years of age. We concluded that BCMA protein is not present in normal adult human brain, and therefore on-target toxicity in the brain is unlikely.

Patterns of CAG repeat instability in the central nervous system and periphery in Huntington's disease and in spinocerebellar ataxia type 1

The expanded HTT CAG repeat causing Huntington’s disease (HD) exhibits somatic expansion proposed to drive the rate of disease onset by eliciting a pathological process that ultimately claims vulnerable cells. To gain insight into somatic expansion in humans, we performed comprehensive quantitative analyses of CAG expansion in ~50 central nervous system (CNS) and peripheral postmortem tissues from seven adult-onset and one juvenile-onset HD individual. We also assessed ATXN1 CAG repeat expansion in brain regions of an individual with a neurologically and pathologically distinct repeat expansion disorder, spinocerebellar ataxia type 1 (SCA1). Our findings reveal similar profiles of tissue instability in all HD individuals, which, notably, were also apparent in the SCA1 individual. CAG expansion was observed in all tissues, but to different degrees, with multiple cortical regions and neostriatum tending to have the greatest instability in the CNS, and liver in the periphery. These patterns indicate different propensities for CAG expansion contributed by disease locus-independent trans-factors and demonstrate that expansion per se is not sufficient to cause cell type or disease-specific pathology. Rather, pathology may reflect distinct toxic processes triggered by different repeat lengths across cell types and diseases. We also find that the HTT CAG length-dependent expansion propensity of an individual is reflected in all tissues and in cerebrospinal fluid. Our data indicate that peripheral cells may be a useful source to measure CAG expansion in biomarker assays for therapeutic efforts, prompting efforts to dissect underlying mechanisms of expansion that may differ between the brain and periphery.

TAMI-28. DIFFERENTIAL MIGRATION MECHANICS AND IMMUNE RESPONSES OF GLIOMA SUBTYPES

In Glioblastoma (GBM), tumor spreading is driven by tumor cells’ ability to infiltrate healthy brain parenchyma, which prevents complete surgical resection and contributes to tumor recurrence. GBM molecular subtypes, classical, proneural and mesenchymal, were shown to strongly correlate with specific genetic alterations (Mesenchymal: NF1; Classical: EGFRVIII; Proneural: PDGFRA). Here we tested the hypothesis that a key mechanistic difference between GBM molecular subtypes is that proneural cells are slow migrating and mesenchymal cells are fast migrating. Using Sleeping Beauty transposon system, immune-competent murine brain tumors were induced by SV40-LgT antigen in combination with either NRASG12V (NRAS) or PDGFB (PDGF) overexpression. Cross-species transcriptomic analysis revealed NRAS and PDGF-driven tumors correlate with human mesenchymal and proneural GBM, respectively. Similar to human GBM, CD44 expression was higher in NRAS tumors and, consistent with migration simulations of varying CD44 levels, ex vivo brain slice live imaging showed NRAS tumors cells migrate faster than PDGF tumors cells (random motility coefficient = 30µm2/hr vs. 2.5µm2/hr, p < 0.001). Consistent with CD44 function as an adhesion molecule, migration phenotype was independent of the tumor microenvironment. NRAS and human PDX/MES tumor cells were found to migrate faster and have larger cell spread area than PDGF and human PDX/PN tumors cells, respectively, in healthy mouse brain slices. Furthermore, traction force microscopy revealed NRAS tumor cells generate larger traction forces than PDGF tumors cells which further supports our theoretical mechanism driving glioma migration. Despite increased migration, NRAS cohort had better survival than PDGF which was attributed to enhanced antitumoral immune response in NRAS tumors, consistent with increased immune cell infiltration found in human mesenchymal GBM. Overall our work identified a potentially actionable difference in migration mechanics between GBM subtypes and establishes an integrated biophysical modeling and experimental approach to mechanically parameterize and simulate distinct molecular subtypes in preclinical models of cancer.

Tract-specific analysis improves sensitivity of spinal cord diffusion MRI to cross-sectional and longitudinal changes in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a late-onset fatal neurodegenerative disease that causes progressive degeneration of motor neurons in the brain and the spinal cord. Corticospinal tract degeneration is a defining feature of ALS. However, there have been very few longitudinal, controlled studies assessing diffusion MRI (dMRI) metrics in different fiber tracts along the spinal cord in general or the corticospinal tract in particular. Here we demonstrate that a tract-specific analysis, with segmentation of ascending and descending tracts in the spinal cord white matter, substantially increases the sensitivity of dMRI to disease-related changes in ALS. Our work also identifies the tracts and spinal levels affected in ALS, supporting electrophysiologic and pathologic evidence of involvement of sensory pathways in ALS. We note changes in diffusion metrics and cord cross-sectional area, with enhanced sensitivity to disease effects through a multimodal analysis, and with strong correlations between these metrics and spinal components of ALSFRS-R.

Oligodendroglioma with Neuronal Differentiation in Two Boxer Dogs

Two cases of high-grade glioma comprising sheets of oligodendroglial cells multifocally disrupted by regions of remarkable neuronal differentiation are described. These tumours morphologically resemble 'oligodendroglioma with ganglioglioma-like maturation', a rare tumour of man, but appear to be phenotypically more aggressive. Neuronal markers (synaptophysin, neuron-specific enolase and βIII-tubulin) effectively highlight neuronal elements within these tumours and could potentially help to further investigate the prevalence and biological significance of neuronal differentiation in canine oligodendroglioma.

Rituximab treatment for isolated IgG4-related hypophysitis in a teenage female

IgG4-related hypophysitis is an important diagnostic consideration in patients with a pituitary mass or pituitary dysfunction and can initially present with headaches, visual field deficits and/or endocrine dysfunction. Isolated IgG4-related pituitary disease is rare, with most cases of IgG4-related disease involving additional organ systems. We report the case of a teenage female patient with isolated IgG4-related hypophysitis, diagnosed after initially presenting with headaches. Our patient had no presenting endocrinologic abnormalities. She was treated with surgical resection, prednisolone and rituximab with no further progression of disease and sustained normal endocrine function. This case, the youngest described patient with isolated IgG4-related hypophysitis and uniquely lacking endocrinologic abnormalities, adds to the limited reports of isolated pituitary disease. The use of rituximab for isolated pituitary disease has never been described. While IgG4-related hypophysitis has been increasingly recognized, substantial evidence concerning the appropriate treatment and follow-up of these patients is largely lacking. Learning points: IgG4-related hypophysitis most often occurs in the setting of additional organ involvement but can be an isolated finding. This diagnosis should therefore be considered in a patient presenting with pituitary abnormalities. Most patients with IgG4-related hypophysitis will have abnormal pituitary function, but normal functioning does not exclude this diagnosis. Corticosteroids have been the mainstay of therapy for IgG4-related disease, with other immunosuppressive regimens being reserved for refractory cases. Further research is needed to understand the effectiveness of corticosteroid-sparing regimens and whether there is utility in using these agents as first-line therapies.

Antisense oligonucleotide-mediated ataxin-1 reduction prolongs survival in SCA1 mice and reveals disease-associated transcriptome profiles

Spinocerebellar ataxia type 1 (SCA1) is a dominantly inherited ataxia caused by expansion of a translated CAG repeat encoding a glutamine tract in the ataxin-1 (ATXN1) protein. Despite advances in understanding the pathogenesis of SCA1, there are still no therapies to alter its progressive fatal course. RNA-targeting approaches have improved disease symptoms in preclinical rodent models of several neurological diseases. Here, we investigated the therapeutic capability of an antisense oligonucleotide (ASO) targeting mouse Atxn1 in Atxn1154Q/2Q-knockin mice that manifest motor deficits and premature lethality. Following a single ASO treatment at 5 weeks of age, mice demonstrated rescue of these disease-associated phenotypes. RNA-sequencing analysis of genes with expression restored to WT levels in ASO-treated Atxn1154Q/2Q mice was used to demonstrate molecular differences between SCA1 pathogenesis in the cerebellum and disease in the medulla. Finally, select neurochemical abnormalities detected by magnetic resonance spectroscopy in vehicle-treated Atxn1154Q/2Q mice were reversed in the cerebellum and brainstem (a region containing the pons and the medulla) of ASO-treated Atxn1154Q/2Q mice. Together, these findings support the efficacy and therapeutic importance of directly targeting ATXN1 RNA expression as a strategy for treating both motor deficits and lethality in SCA1.

SCA8 RAN polySer protein preferentially accumulates in white matter regions and is regulated by eIF3F

Spinocerebellar ataxia type 8 (SCA8) is caused by a bidirectionally transcribed CTG·CAG expansion that results in the in vivo accumulation of CUG RNA foci, an ATG-initiated polyGln and a polyAla protein expressed by repeat-associated non-ATG (RAN) translation. Although RAN proteins have been reported in a growing number of diseases, the mechanisms and role of RAN translation in disease are poorly understood. We report a novel toxic SCA8 polySer protein which accumulates in white matter (WM) regions as aggregates that increase with age and disease severity. WM regions with polySer aggregates show demyelination and axonal degeneration in SCA8 human and mouse brains. Additionally, knockdown of the eukaryotic translation initiation factor eIF3F in cells reduces steady-state levels of SCA8 polySer and other RAN proteins. Taken together, these data show polySer and WM abnormalities contribute to SCA8 and identify eIF3F as a novel modulator of RAN protein accumulation.

Polarization-sensitive optical coherence tomography reveals gray matter and white matter atrophy in SCA1 mouse models

Spinocerebellar ataxia type 1 (SCA1) is a fatal inherited neurodegenerative disease. In this study, we demonstrate the label-free optical imaging methodology that can detect, with a high degree of sensitivity, discrete areas of degeneration in the cerebellum of the SCA1 mouse models. We used ATXN1[82Q] and ATXN1[30Q]-D776 mice in which the transgene is directed only to Purkinje cells. Molecular layer, granular layer, and white matter regions are analyzed using the intrinsic contrasts provided by polarization-sensitive optical coherence tomography. Cerebellar atrophy in SCA1 mice occurred both in gray matter and white matter. While gray matter atrophy is obvious, indications of white matter atrophy including different birefringence characteristics, and shortened and contorted branches are observed. Imaging results clearly show the loss or atrophy of myelinated axons in ATXN1[82Q] mice. The method provides unbiased contrasts that can facilitate the understanding of the pathological progression in neurodegenerative diseases and other neural disorders.

Effect of Gamma Knife Radiosurgery and Programmed Cell Death 1 Receptor Antagonists on Metastatic Melanoma

Learning objectives

To evaluate radiation-induced changes in patients with brain metastasis secondary to malignant melanoma who received treatment with Gamma Knife radiosurgery (GKRS) and programmed cell death 1 (PD-1) receptor antagonists.

Introduction 

Stereotactic radiosurgery and chemotherapeutics are used together for treatment of metastatic melanoma and have been linked to delayed radiation-induced vasculitic leukoencephalopathy (DRIVL). There have been reports of more intense interactions with new immunotherapeutics targeting PD-1 receptors, but their interactions have not been well described and may result in an accelerated response to GKRS. Here we present data on subjects treated with this combination from a single institution.

Methods

Records from patients who underwent treatment for metastatic melanoma to the brain with GKRS from 2011 to 2016 were reviewed. Demographics, date of brain metastasis diagnosis, cause of death when applicable, immunotherapeutics, and imaging findings were recorded. The timing of radiation therapy and medications were also documented. 

Results

A total of 79 subjects were treated with GKRS, and 66 underwent treatment with both GKRS and immunotherapy. Regarding the 30 patients treated with anti-PD-1 immunotherapy, 21 patients received pembrolizumab, seven patients received nivolumab, and two patients received pembrolizumab and nivolumab. Serial imaging was available for interpretation in 25 patients, with 13 subjects who received GKRS and anti-PD-1 immunotherapy less than six weeks of each other. While four subjects had indeterminate/mixed findings on subsequent magnetic resonance imaging (MRI), nine subjects were noted to have progression. Two of these patients showed progression but subsequent imaging revealed a decrease in progression or improvement on MRI to previously targeted lesions by GKRS. None of the 13 subjects had surgery following their combined therapies.

Conclusions

This data suggests that there is need for further investigation of the role for concurrent treatment with PD-1 inhibitors and GKRS to enhance the treatment of metastatic melanoma. We present data on 13 patients who appear to have some radiologic benefit to this treatment combination, two of whom had radiographic pseudoprogression.

RAN Translation Regulated by Muscleblind Proteins in Myotonic Dystrophy Type 2

Several microsatellite-expansion diseases are characterized by the accumulation of RNA foci and RAN proteins, raising the possibility of a mechanistic connection. We explored this question using myotonic dystrophy type 2, a multisystemic disease thought to be primarily caused by RNA gain-of-function effects. We demonstrate that the DM2 CCTG⋅CAGG expansion expresses sense and antisense tetrapeptide poly-(LPAC) and poly-(QAGR) RAN proteins, respectively. In DM2 autopsy brains, LPAC is found in neurons, astrocytes, and glia in gray matter, and antisense QAGR proteins accumulate within white matter. LPAC and QAGR proteins are toxic to cells independent of RNA gain of function. RNA foci and nuclear sequestration of CCUG transcripts by MBNL1 is inversely correlated with LPAC expression. These data suggest a model that involves nuclear retention of expansion RNAs by RNA-binding proteins (RBPs) and an acute phase in which expansion RNAs exceed RBP sequestration capacity, are exported to the cytoplasm, and undergo RAN translation. VIDEO ABSTRACT.

Neonatal Respiratory Failure Caused by Congenital Diffuse Intrinsic Pontine Glioma

The authors present a case of diffuse intrinsic pontine glioma presenting in a newborn with stridor and respiratory distress that progressed to respiratory failure. Magnetic resonance imaging (MRI) of the brain revealed findings compatible with the diagnosis of diffuse intrinsic pontine glioma. The family pursued palliative care and postmortem examination confirmed WHO grade III astrocytoma.

Report of effective trametinib therapy in 2 children with progressive hypothalamic optic pathway pilocytic astrocytoma: documentation of volumetric response

Brain tumors are the most common solid tumor in childhood, and astrocytomas account for the largest proportion of these tumors. Increasing sophistication in genetic testing has allowed for the detection of specific mutations within tumor subtypes that may represent targets for individualized tumor treatment. The mitogen-activating protein kinase (MAPK) pathway and, more specifically, BRAF mutations have been shown to be prevalent in pediatric pilocytic astrocytomas and may represent one such area to target. Herein, the authors describe 2 cases of inoperable, chemotherapy-resistant pediatric pilocytic astrocytomas with a documented response to trametinib, an MAPK pathway inhibitor. While these cases were not treated in the setting of a clinical trial, their data support further ongoing clinical trial investigation to evaluate the safety and efficacy of this agent in pediatric low-grade gliomas.

Isolated Hypertrophic Neuropathy of the Oculomotor Nerve

BACKGROUND

Hypertrophic neuropathy is a rare entity commonly associated with peripheral nerve, characterized by onion bulb formations. Its cranial nerve involvement is very rare; only 7 cases have been found in the literature.

CASE DESCRIPTION

A 32-year-old white man with a 5-year history of intermittent right retro-orbital headache and mild right ptosis presented to the Neurosurgery Clinic. A magnetic resonance imaging of his brain demonstrated an enhancing lesion associated with the right third nerve. He underwent biopsy of the lesion, and its pathology report confirmed the diagnosis of hypertrophic neuropathy. Within 4 months, his third nerve palsy had completely resolved and was functioning fully.

CONCLUSIONS

Here, we report a first case of isolated hypertrophic neuropathy involving the oculomotor nerve.

Chronic Traumatic Encephalopathy in Athletes Involved with High-impact Sports

BACKGROUND AND PURPOSE

Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease occurring most commonly in athletes and is caused by repeated concussive or subconcussive blows to the head. The main purpose of this review is to evaluate the published literature on chronic traumatic encephalopathy (CTE) in athletes participating in high-impact sports. In particular, we highlight the significance of concussive and subconcussive impacts in multiple sports, elucidate the differences between clinical/pathological features of CTE and related neurodegenerative diseases, and provide an explanation for the variation in clinical presentation between athletes of different sports.

METHODS

A review targeting relevant publications to CTE was performed. The PubMed/MEDLINE index was searched for keywords such as "chronic traumatic encephalopathy," "repetitive traumatic brain injury," "mild traumatic brain injury," and "concussion" from year 1924 through March 1, 2016.

RESULTS

A consensus panel's recent identification of a pathognomonic pathology in CTE, characterized by an irregular distribution of phosphorylated tau deposits, is an important step in developing consensus diagnostic criteria and clinicopathological studies. After review of major clinical studies, evidence suggests that there are clear differences in neuropathological features, clinical progression, and manifestation of symptoms between CTE and other neurodegenerative diseases. The literature suggests boxers tend to have more severe symptoms than other athletes due to more frequent rotational and shearing impacts. Data regarding genetic predispositions of CTE have been inconsistent in part due to low subject populations. Positron emission tomography imaging involving tau-binding ligands has recently proven effective in differentiating CTE from control groups and other neurodegenerative diseases.

CONCLUSIONS

Further longitudinal studies should be conducted to correlate the number of suffered concussive/subconcussive forces to the likelihood of developing chronic traumatic brain injury symptoms. Research striving for a reliable antemortem CTE diagnosis would be immensely beneficial, leading to more accurate estimates of prevalence, allowing clinicians to assess future risk of athletes' continued participation in sports, and enabling clinicians to make appropriate preventive recommendations.

Peripheral Facial Nerve Regeneration Using Collagen Conduit Entubulation in a Cat Model

Objectives:

Facial nerve (FN) injuries are functionally, psychologically, and financially debilitating. Facial nerve autograft repairs produce significant donor nerve morbidity and functional results that rarely exceed House-Brackmann (HB) grade III over VI. In this study we sought to enhance FN regeneration via collagen conduit entubulation.

Methods:

Five control cats underwent right (“cut-side”) FN transection and immediate microsurgical anastomosis repair. Five experimental cats underwent identical repairs plus collagen conduit entubulation of each anastomosis.

Results:

Postoperative behavioral observations revealed gradual FN functional recovery in all cats, who attained adapted HB grades of II to III over VI after 6 weeks. Electromyographic latencies and amplitudes from the bilateral orbicularis oculi and orbicularis oris muscles indicated restoration of FN continuity in all 10 cats. In comparison with FN repairs without conduits, repairs with conduits significantly enhanced recovery of amplitude in cut-side orbicularis oculi muscles (p = .037) and latency in cut-side orbicularis oris muscles (p = .048). In comparison with intact left (“uncut-side”) FN latencies and amplitudes, more statistically significant differences in cut-side FN function were observed in repairs without conduits than in repairs with conduits. Conduits therefore facilitated a more complete return of electrophysiological function. Histologic analyses confirmed FN continuity and revealed more organized FN regenerative architecture in conduit-implanted repairs.

Conclusions:

The overall results support enhanced FN regeneration with collagen conduit entubulation.

MBNL Sequestration by Toxic RNAs and RNA Misprocessing in the Myotonic Dystrophy Brain

For some neurological disorders, disease is primarily RNA mediated due to expression of non-coding microsatellite expansion RNAs (RNA(exp)). Toxicity is thought to result from enhanced binding of proteins to these expansions and depletion from their normal cellular targets. However, experimental evidence for this sequestration model is lacking. Here, we use HITS-CLIP and pre-mRNA processing analysis of human control versus myotonic dystrophy (DM) brains to provide compelling evidence for this RNA toxicity model. MBNL2 binds directly to DM repeat expansions in the brain, resulting in depletion from its normal RNA targets with downstream effects on alternative splicing and polyadenylation. Similar RNA processing defects were detected in Mbnl compound-knockout mice, highlighted by dysregulation of Mapt splicing and fetal tau isoform expression in adults. These results demonstrate that MBNL proteins are directly sequestered by RNA(exp) in the DM brain and introduce a powerful experimental tool to evaluate RNA-mediated toxicity in other expansion diseases.

Vaccination with dendritic cells loaded with allogeneic brain tumor cells for recurrent malignant brain tumors induces a CD4(+)IL17(+) response

BACKGROUND

We tested the hypothesis that a novel vaccine developed from autologous dendritic cells (DC) loaded with cells from a unique allogeneic brain tumor cell line (GBM6-AD) would be well-tolerated and would generate an immune response.

METHOD

Patients with recurrent primary brain tumors underwent vaccination with GBM6-AD/DC vaccine. Subjects were treated at escalating DC cell doses: 5 × 10(6) (one patient), 10 × 10(6) (one patient) and 15 × 10(6) (6 patients). Subcutaneous injections were planned for days 0, 14, 28, 42, 56, and monthly thereafter. The primary endpoint was the safety of the GBM6-AD/DC vaccination. The secondary endpoints were immune response, measured by flow cytometry, and the clinical outcome of tumor response defined by time to progression and overall survival.

RESULTS

Eight patients were treated. The first three patients were treated in the dose escalation phase of the trial; the remaining five patients received the maximum dose of 15 × 10(6) DC. No dose limiting toxicity was observed. The best response per modified McDonald criteria was partial response in one patient. Flow cytometric immune profiling revealed significant differences in CD4(+)IL17(+) lymphocytes and myeloid derived suppressor cell populations between patients characterized as having stable vs. non-stable disease.

CONCLUSION

This first-in-human study shows that the GBM6-AD/DC vaccine was well tolerated and was associated with an immune response in a subset of patients. No MTD was achieved in this trial. This small-scale pilot provides information for larger scale investigations into the use of this allogeneic vaccine source.

Brown-Vialetto-Van Laere syndrome: clinical and neuropathologic findings with immunohistochemistry for C20orf54 in three affected patients

Brown-Vialetto-Van Laere syndrome (BVVLS) is a rare degenerative neurological disorder characterized by pontobulbar palsy and sensorineural deafness. Since its initial description in 1894, fewer than 100 cases have been reported, and published neuropathological analyses of these cases are extremely rare. Recently, individuals with BVVLS have been found to carry mutations in the C20orf54 gene, which encodes the human homolog for a rat riboflavin transporter. We present the case of a male who presented at the age of 5 years with sensorineural deafness, as well as those of 2 infant sisters who presented at 11 and 13 months of age with weakness and ataxia, respectively. All cases were genetically confirmed. We include the 1st immunohistochemical characterization of C20orf54 expression in BVVLS and controls. Results showed punctate axonal staining in the control cases that was dramatically reduced in the 3 BVVLS cases compared to the 5 controls. This decreased staining was seen even in the neocortex, which was unaffected in the BVVLS cases by routine histology. While the implications of these results are far from definitive, and although the evaluation of more cases is needed, immunohistochemistry for the C20orf54 protein may eventually be useful, in the right clinical scenario, as a screening test when selecting cases for sequencing of the C20orf54 gene to diagnose BVVLS at autopsy.

Intracranial-derived atherosclerosis assessment: an in vitro comparison between virtual histology by intravascular ultrasonography, 7T MRI, and histopathologic findings

BACKGROUND AND PURPOSE

Atherosclerotic plaque composition and structure contribute to the risk of plaque rupture and embolization. Virtual histology by intravascular ultrasonography and high-resolution MR imaging are new imaging modalities that have been used to characterize plaque morphology and composition in peripheral arteries.

MATERIALS AND METHODS

The objectives of this study were 1) to determine the correlation between virtual histology-intravascular ultrasonography and histopathologic analysis (reference standard) and 2) to explore the comparative results of 7T MR imaging (versus histopathologic analysis), both to be performed in vitro by use of intracranial arterial segments with atherosclerotic plaques. Thirty sets of postmortem samples of intracranial circulation were prepared for the study. These samples included the middle cerebral artery (n = 20), basilar artery (n = 8), and anterior cerebral artery (n = 2). Virtual histology-intravascular ultrasonography and 7T MR imaging were performed in 34 and 10 points of interest, respectively. The formalin-fixed arteries underwent tissue processing and hematoxylin-eosin staining. The plaques were independently categorized according to revised Stary classification after review of plaque morphology and characteristics obtained from 3 modalities. The proportion of fibrous, fibrofatty, attenuated calcium, and necrotic components in the plaques were determined in histology slides and compared with virtual histology-intravascular ultrasonography and MR imaging.

RESULTS

Of 34 points of interest in the vessels, 32 had atherosclerotic plaques under direct visualization. Plaques were visualized in gray-scale intravascular ultrasonography as increased wall thickness, outer wall irregularity, and protrusion. The positive predictive value of virtual histology-intravascular ultrasonography for identifying fibroatheroma was 80%. Overall, virtual histology-intravascular ultrasonography accurately diagnosed the type of the plaque in 25 of 34 samples, and κ agreement was 0.58 (moderate agreement). The sensitivity and specificity of virtual histology-intravascular ultrasonography readings for fibroatheroma were 78.9% and 73.3%, respectively. The overall sensitivity and specificity for virtual histology-intravascular ultrasonography were 73.5% and 96.6%, respectively. Plaques were identified in 7T MR imaging as increased wall thickness, luminal stenosis, or outer wall protrusion. The positive predictive value of 7T MR imaging for detecting fibrous and attenuated calcium deposits was 88% and 93%, respectively.

CONCLUSIONS

This in vitro study demonstrated that virtual histology-intravascular ultrasonography and high-resolution MR imaging are reliable imaging tools to detect atherosclerotic plaques within the intracranial arterial wall, though both imaging modalities have some limitations in accurate characterization of the plaque components. Further clinical studies are needed to determine the clinical utility of plaque morphology and composition assessment by noninvasive tests.

CSF1R mutations link POLD and HDLS as a single disease entity

OBJECTIVE

Pigmented orthochromatic leukodystrophy (POLD) and hereditary diffuse leukoencephalopathy with axonal spheroids (HDLS) are rare neurodegenerative disorders characterized by cerebral white matter abnormalities, myelin loss, and axonal swellings. The striking overlap of clinical and pathologic features of these disorders suggested a common pathogenesis; however, no genetic or mechanistic link between POLD and HDLS has been established. Recently, we reported that mutations in the colony-stimulating factor 1 receptor (CSF1R) gene cause HDLS. In this study, we determined whether CSF1R mutations are also a cause of POLD.

METHODS

We performed sequencing of CSF1R in 2 pathologically confirmed POLD families. For the largest family (FTD368), a detailed case report was provided and brain samples from 2 affected family members previously diagnosed with POLD were re-evaluated to determine whether they had HDLS features. In vitro functional characterization of wild-type and mutant CSF1R was also performed.

RESULTS

We identified CSF1R mutations in both POLD families: in family 5901, we found c.2297T>C (p.M766T), previously reported by us in HDLS family CA1, and in family FTD368, we identified c.2345G>A (p.R782H), recently reported in a biopsy-proven HDLS case. Immunohistochemical examination in family FTD368 showed the typical neuronal and glial findings of HDLS. Functional analyses of CSF1R mutant p.R782H (identified in this study) and p.M875T (previously observed in HDLS), showed a similar loss of CSF1R autophosphorylation of selected tyrosine residues in the kinase domain for both mutations when compared with wild-type CSF1R.

CONCLUSIONS

We provide the first genetic and mechanistic evidence that POLD and HDLS are a single clinicopathologic entity.

Muscleblind-like 2-mediated alternative splicing in the developing brain and dysregulation in myotonic dystrophy

The RNA-mediated disease model for myotonic dystrophy (DM) proposes that microsatellite C(C)TG expansions express toxic RNAs that disrupt splicing regulation by altering MBNL1 and CELF1 activities. While this model explains DM manifestations in muscle, less is known about the effects of C(C)UG expression on the brain. Here, we report that Mbnl2 knockout mice develop several DM-associated central nervous system (CNS) features including abnormal REM sleep propensity and deficits in spatial memory. Mbnl2 is prominently expressed in the hippocampus and Mbnl2 knockouts show a decrease in NMDA receptor (NMDAR) synaptic transmission and impaired hippocampal synaptic plasticity. While Mbnl2 loss did not significantly alter target transcript levels in the hippocampus, misregulated splicing of hundreds of exons was detected using splicing microarrays, RNA-seq, and HITS-CLIP. Importantly, the majority of the Mbnl2-regulated exons examined were similarly misregulated in DM. We propose that major pathological features of the DM brain result from disruption of the MBNL2-mediated developmental splicing program.

A conserved eEF2 coding variant in SCA26 leads to loss of translational fidelity and increased susceptibility to proteostatic insult

The autosomal dominant spinocerebellar ataxias (SCAs) are a genetically heterogeneous group of disorders exhibiting cerebellar atrophy and Purkinje cell degeneration whose subtypes arise from 31 distinct genetic loci. Our group previously published the locus for SCA26 on chromosome 19p13.3. In this study, we performed targeted deep sequencing of the critical interval in order to identify candidate causative variants in individuals from the SCA26 family. We identified a single variant that co-segregates with the disease phenotype that produces a single amino acid substitution in eukaryotic elongation factor 2. This substitution, P596H, sits in a domain critical for maintaining reading frame during translation. The yeast equivalent, P580H EF2, demonstrated impaired translocation, detected as an increased rate of -1 programmed ribosomal frameshift read-through in a dual-luciferase assay for observing translational recoding. This substitution also results in a greater susceptibility to proteostatic disruption, as evidenced by a more robust activation of a reporter gene driven by unfolded protein response activation upon challenge with dithiothreitol or heat shock in our yeast model system. Our results present a compelling candidate mutation and mechanism for the pathogenesis of SCA26 and further support the role of proteostatic disruption in neurodegenerative diseases.

Genetically engineered mouse models of the trinucleotide-repeat spinocerebellar ataxias

The spinocerebellar ataxias (SCAs) are dominantly inherited disorders that primarily affect coordination of motor function but also frequently involve other brain functions. The models described in this review address mechanisms of trinucleotide-repeat expansions, particularly those relating to polyglutamine expression in the mutant proteins. Modeling chronic late-onset human ataxias in mice is difficult because of their short life-span. While this potential hindrance has been partially overcome by using over-expression of the mutant gene, and/or worsening of the mutation by increasing the length of the trinucleotide repeat expansion, interpretation of results from such models and extrapolation to the human condition should be cautious. Nevertheless, genetically engineered murine models of these diseases have enhanced our understanding of the pathogenesis of many of these conditions. A common theme in many of the polyglutamine-repeat diseases is nuclear localization of mutant protein, with resultant effects on gene regulation. Conditional mutant models and transgenic knock-down therapy have demonstrated the potential for reversibility of disease when production of mutant protein is halted. Several other genetically engineered murine models of SCA also have begun to show utility in the identification and assessment of more classical drug-based therapeutic modalities.

Massive expansion of SCA2 with autonomic dysfunction, retinitis pigmentosa, and infantile spasms

OBJECTIVE

To provide clinical data on a cohort of 6 patients with massive expansion (>200 CAG repeats) of spinocerebellar ataxia type 2 (SCA2) and investigate possible pathways of pathogenesis using bioinformatics analysis of ATXN2 networks.

METHODS

We present data on 6 patients with massive expansion of SCA2 who presented in infancy with variable combinations of hypotonia, global developmental delay, infantile spasms, and retinitis pigmentosa. ATXN2 is known to interact with a network of synaptic proteins. To investigate pathways of pathogenesis, we performed bioinformatics analysis on ATXN2 combined with known genes associated with infantile spasms, retinitis pigmentosa, and synaptic function.

RESULTS

All patients had a progressive encephalopathy with autonomic dysfunction, 4 had retinitis pigmentosa, and 3 had infantile spasms. The bioinformatics analysis led to several interesting findings. First, an interaction between ATXN2 and SYNJ1 may account for the development of retinitis pigmentosa. Second, dysfunction of postsynaptic vesicle endocytosis may be important in children with this progressive encephalopathy. Infantile spasms may be associated with interactions between ATXN2 and the postsynaptic structural proteins MAGI2 and SPTAN1.

CONCLUSIONS

Severe phenotype in children with massive expansion of SCA2 may be due to a functional deficit in protein networks in the postsynapse, specifically involving vesicle endocytosis.

Neurochemical alterations in spinocerebellar ataxia type 1 and their correlations with clinical status

Robust biomarkers of neurodegeneration are critical for testing of neuroprotective therapies. The clinical applicability of such biomarkers requires sufficient sensitivity to detect disease in individuals. Here we tested the sensitivity of high field (4 tesla) proton magnetic resonance spectroscopy ((1)H MRS) to neurochemical alterations in the cerebellum and brainstem in spinocerebellar ataxia type 1 (SCA1). We measured neurochemical profiles that consisted of 10 to 15 metabolite concentrations in the vermis, cerebellar hemispheres and pons of patients with SCA1 (N = 9) and healthy controls (N = 15). Total NAA (N-acetylaspartate + N-acetylaspartylglutamate, tNAA) and glutamate were lower and glutamine, myo-inositol and total creatine (creatine + phosphocreatine, tCr) were higher in patients relative to controls, consistent with neuronal dysfunction/loss, gliotic activity, and alterations in glutamate-glutamine cycling and energy metabolism. Changes in tNAA, tCr, myo-inositol, and glutamate levels were discernible in individual spectra and the tNAA/myo-inositol ratio in the cerebellar hemispheres and pons differentiated the patients from controls with 100% specificity and sensitivity. In addition, tNAA, myo-inositol, and glutamate levels in the cerebellar hemispheres and the tNAA and myo-inositol levels in the pons correlated with ataxia scores (Scale for the Assessment and Rating of Ataxia, SARA). Two other biomarkers measured in the cerebrospinal fluid (CSF) of a subset of the volunteers (F(2)-isoprostanes asa marker of oxidative stress and glial fibrillary acidic protein (GFAP) as a marker of gliosis) were not different between patients and controls. These data demonstrate that (1)H MRS biomarkers can be utilized to noninvasively assess neuronal and glial status in individual ataxia patients.

(1)H MR spectroscopy in Friedreich's ataxia and ataxia with oculomotor apraxia type 2

BACKGROUND AND AIM

Friedreich's ataxia (FRDA) and ataxia with oculomotor apraxia type 2 (AOA2) are the two most frequent forms of autosomal recessive cerebellar ataxias. However, brain metabolism in these disorders is poorly characterized and biomarkers of the disease progression are lacking. We aimed at assessing the neurochemical profile of the pons, the cerebellar hemisphere and the vermis in patients with FRDA and AOA2 to identify potential biomarkers of these diseases.

METHODS

Short-echo, single-voxel proton ((1)H) magnetic resonance spectroscopy data were acquired from 8 volunteers with FRDA, 9 volunteers with AOA2, and 38 control volunteers at 4T. Disease severity was assessed by the Friedreich's Ataxia Rating Scale (FARS).

RESULTS

Neuronal loss/dysfunction was indicated in the cerebellar vermis and hemispheres in both diseases by lower total N-acetylaspartate levels than controls. The putative gliosis marker myo-inositol was higher than controls in the vermis and pons in AOA2 and in the vermis in FRDA. Total creatine, another potential gliosis marker, was higher in the cerebellar hemispheres in FRDA relative to controls. Higher glutamine in FRDA and lower glutamate in AOA2 than controls were observed in the vermis, indicating different mechanisms possibly leading to altered glutamatergic neurotransmission. In AOA2, total N-acetylaspartate levels in the cerebellum strongly correlated with the FARS score (p<0.01).

CONCLUSION

Distinct neurochemical patterns were observed in the two patient populations, warranting further studies with larger patient populations to determine if the alterations in metabolite levels observed here may be utilized to monitor disease progression and treatment.

Epilepsy: an anticipatory presentation of pediatric Wegener's granulomatosis

Wegener's granulomatosis is a necrotizing, granulomatous vasculitis that primarily affects the respiratory tract and kidneys. It is rare in children. Few pediatric and adult case reports described seizures and central nervous system involvement at initial presentation, and none described central nervous system involvement in the absence of respiratory or renal disease. We describe a 17-year-old girl with secondarily generalized seizures and granulomatous lesions in her brain. Although a systemic inflammatory disorder was suspected, she lacked evidence of pulmonary or renal involvement, so her signs were initially labeled as postinfectious encephalitis or variant acute disseminated encephalomyelitis. After 1 year of immunosuppressive therapy, she developed additional signs, leading to histologic confirmation on lung biopsy of Wegener's granulomatosis. This case emphasizes the need for close follow-up to monitor the asynchronous development of diagnostic clues when a systemic vasculitis is suspected but cannot be confirmed.

A parent advice package for family shopping trips: development and evaluation

THIS ARTICLE REPORTS ON THE PRIMARY STEPS IN THE DEVELOPMENT OF PARENT ADVICE FOR POPULAR DISSEMINATION: (a) developing advice for one specific problem situation, family shopping trips; (b) testing the advice program for benefit to children and convenience to adults; and (c) packaging the advice so it can be used successfully by interested parents. Systematic observation of 12 families using the written advice package on shopping trips revealed its effectiveness in reducing child disruptions and increasing positive interactions between parents and children. These findings, along with interview information from families, showed that the package is usable, effective, and popular with both parents and children, and thus is ready for dissemination to a wide audience of parents-a step that in itself should involve research and evaluation.

A classroom program teaching disadvantaged youths to write biographic information

Little attention has been given to how formal classroom instruction can be adapted to teach youths everyday skills such as the correct writing of biographic information frequently requested in transactions like applying for a job or a social security number and cashing a check. In this study, six youths in a special education classroom were taught to complete job application forms with the date, their name, signature, address, telephone number, date of birth, and a reference's name, address, and occupation. Each youth was trained on one item of biographic information at a time, after which he was tested on four application forms, including one on which he had not been trained. The tests show that after an item had been taught, it was correctly used in completing application forms on which the youths had been trained and forms on which they had never been trained. The study demonstrates the feasibility of teaching community-living, vocation-related skills to special-education youths in a classroom setting.

Peer tutoring among elementary students: educational benefits to the tutor

To determine whether tutoring might be academically beneficial to the tutor, this study investigated the acquisition of spelling words by three elementary students in a peer tutoring program. The experimental design allowed a simultaneous comparison of each child's gain in performance on comparable word lists on which the child tutored another child, was tutored by another child, or neither gave nor received tutoring. The children's spelling improved nearly an equivalent amount on those words on which they tutored another child as on the words on which they were tutored; no such change was noted on the words on which they neither gave nor received tutoring. These findings, that peer tutoring is profitable for the tutor as well as the tutee, provide a basis for recommending peer tutoring as one method of individualizing education.

Timeout as a punishing stimulus in continuous and intermittent schedules

The effectiveness of a brief period of isolation (timeout) in the control of disruptive behavior emitted by a retarded child in a preschool classroom setting was examined. Timeout was shown to be an effective punishing stimulus, and its control of the child's disruptive behavior was investigated under four schedules of intermittent timeout. The results suggest that as a larger percentage of responses were punished, a greater decrease in the frequency of that response occurred. This inverse relationship between the percentage of responses punished and the frequency of the response did not appear to be linear, but rather a non-linear function. This function suggests that some schedules of intermittent punishment may be as effective as continuous punishment, at least in the case of the continued suppression of a response that has already been reduced to a low frequency.

Effects of a conditioned reinforcer upon accuracy of match-to-sample behavior in pigeons

Three pigeons were trained to perform a two-key sequential match-to-sample task. During baseline conditions, food reinforcement was contingent upon the first match response to occur following 8-min periods, and orange illumination of both keys preceded the delivery of food by 0.5 sec. The baseline schedule of food reinforcement was in effect throughout the study. In some conditions, a 0.5-sec flash of orange keylight alone was presented contingent upon mismatch responses that followed variable time periods averaging 1 min. Rate of mismatch responses increased and accuracy of matching performances decreased as compared with baseline conditions. The ability of the 0.5-sec orange flash to reinforce mismatch responses was markedly reduced when it no longer immediately preceded the delivery of food.

Phosphorylation of ATXN1 at Ser776 in the cerebellum

Spinocerebellar ataxia type 1 (SCA1) is one of nine inherited neurodegenerative disorders caused by a mutant protein with an expanded polyglutamine tract. Phosphorylation of ataxin-1 (ATXN1) at serine 776 is implicated in SCA1 pathogenesis. Previous studies, utilizing transfected cell lines and a Drosophila photoreceptor model of SCA1, suggest that phosphorylating ATXN1 at S776 renders it less susceptible to degradation. This work also indicated that oncogene from AKR mouse thymoma (Akt) promotes the phosphorylation of ATXN1 at S776 and severity of neurodegeneration. Here, we examined the phosphorylation of ATXN1 at S776 in cerebellar Purkinje cells, a prominent site of pathology in SCA1. We found that while phosphorylation of S776 is associated with a stabilization of ATXN1 in Purkinje cells, inhibition of Akt either in vivo or in a cerebellar extract-based phosphorylation assay did not decrease the phosphorylation of ATXN1-S776. In contrast, immunodepletion and inhibition of cyclic AMP-dependent protein kinase decreased phosphorylation of ATXN1-S776. These results argue against Akt as the in vivo kinase that phosphorylates S776 of ATXN1 and suggest that cyclic AMP-dependent protein kinase is the active ATXN1-S776 kinase in the cerebellum.

Characterization of the zebrafish atxn1/axh gene family

In mammals, ataxin-1 (ATXN1) is a member of a family of proteins in which each member contains an AXH domain. Expansion of the polyglutamine tract in ATXN1 causes the neurodegenerative disease, spinocerebellar ataxia type 1 (SCA1) with prominent cerebellar pathology. Toward a further characterization of the genetic diversification of the ATXN1/AXH gene family, we identified and characterized members of this gene family in zebrafish, a lower vertebrate with a cerebellum. The zebrafish genome encodes two ATXN1 homologs, atxn1a and atxn1b, and one ATXN1L homolog, atxn1l. Key biochemical features of the human ATXN1 protein not seen in the invertebrate homologs (a nuclear localization sequence and a site of phosphorylation at serine 776) are conserved in the zebrafish homologs, and all three zebrafish Atxn1/Axh proteins behave similarly to their human counterparts in tissue-culture cells. Importantly, each of the three homologs is expressed in the zebrafish cerebellum, which in humans, is a prominent site of SCA1 pathogenesis. In addition, atxn1a and atxn1b are expressed in the developing zebrafish cerebellum. These data show that in zebrafish, a lower vertebrate, the complexity of the atxn1/axh gene family is more similar to higher vertebrates than invertebrates with a simple central nervous system and suggests a relationship between the diversification of the ATXN1/AXH gene family and the development of a complex central nervous system, including a cerebellum.

Mouse models of human CAG repeat disorders

Expansions of CAG trinucleotide repeats encoding glutamine have been found to be the causative mutations of seven human neurodegenerative diseases. Similarities in the clinical, genetic, and molecular features of these disorders suggest they share a common mechanism of pathogenesis. Recent progress in the generation and characterization of transgenic mice expressing the genes containing expanded repeats associated with spinal and bulbar muscular atrophy (SBMA), spinocerebellar ataxia type 1 (SCA1), Machado-Joseph disease (MJD/SCA3), and Huntington's disease (HD) is beginning to provide insight into the underlying mechanisms of these neurodegenerative disorders.

A pediatric case of low-grade lymphomatoid granulomatosis presenting with a cerebellar mass

Lymphomatoid granulomatosis (LA) is a rare angiocentric lymphoreticular proliferative disease that primarily involves the lungs but may also involve extrapulmonary sites including the central nervous system, skin, and kidneys. It is rare for this condition to affect children, and presentation as a cerebellar mass is unusual. In this report, we describe a 10-year-old girl with biopsy-proved cerebellar LA.

Use of therapeutic plasma exchange in the management of acute hemorrhagic leukoencephalitis: a case report and review of the literature

BACKGROUND

Acute hemorrhagic leukoencephalitis (AHLE) is a rare, fatal, central nervous demyelinating disease characterized by a rapid fulminant clinical course. Successful management requires early diagnosis, aggressive management of cerebral edema, and immunosuppression. Therapeutic plasma exchange (TPE) is infrequently used and commences after initial management fails.

CASE REPORT

A 31-year-old man presented with right arm weakness, whose symptoms rapidly progressed to hemiplegia and aphasia. The patient was initially managed with glucocorticosteroids. Decompressive craniotomy and brain biopsies were performed when his intracranial pressure increased. Brain biopsy findings were consistent with AHLE. Mycoplasma pneumonia immunoglobulin G and immunoglobulin M serologies revealed recent infection. Despite surgical and medical management, he decompensated on Day 11, and TPE was initiated. The patient received a total of 10 TPE treatments. On the fourth day of TPE treatment, he was extubated. Twenty-one days after TPE began, he was ambulating with near normal muscle strength and was discharged. Four months after initial presentation, the patient has normal strength and is working full-time.

CONCLUSIONS

AHLE has a fulminant course requiring accurate and rapid diagnosis. Successful therapy requires aggressive management of intracranial pressure and immunosuppression. Two other reports of AHLE document successful management with TPE. Each of these patients survived with minimal neurologic impairments. Given the likely immune-mediated nature of this disease, combined treatment of steroids, surgery, and TPE may lead to shorter hospital stays and improved neurologic outcomes. Clinical studies are needed to further study the effect of TPE on neurologic outcome in AHLE.

RORalpha-mediated Purkinje cell development determines disease severity in adult SCA1 mice

Spinocerebellar ataxia type 1 (SCA1) is one of nine inherited, typically adult onset, polyglutamine neurodegenerative diseases. To examine whether development impacts SCA1, we used a conditional transgenic mouse model of SCA1 to delay the postnatal expression of mutant ATXN1 until after completion of cerebellar development. Delayed postnatal expression of mutant ATXN1 led to a substantial reduction in severity of disease in adults in comparison with early postnatal gene expression. This was linked to a destabilization of RORalpha, a transcription factor critical for cerebellar development. In SCA1 mice, there was a depletion of RORalpha and a reduction in expression of genes controlled by RORalpha. Partial loss of RORalpha enhanced mutant ATXN1 pathogenicity. Additionally, evidence points to the existence of a complex containing ATXN1, RORalpha, and the RORalpha coactivator Tip60. These studies indicate RORalpha and Tip60 have a role in SCA1 and suggest a mechanism by which compromising cerebellar development contributes to severity of neurodegeneration in an adult.

Targeted deletion of a single Sca8 ataxia locus allele in mice causes abnormal gait, progressive loss of motor coordination, and Purkinje cell dendritic deficits

Spinocerebellar ataxia type 8 (SCA8) patients typically have a slowly progressive, adult-onset ataxia. SCA8 is dominantly inherited and is caused by large CTG repeat expansions in the untranslated antisense RNA of the Kelch-like 1 gene (KLHL1), but the molecular mechanism through which this expansion leads to disease is still unknown. To more fully characterize the underlying molecular mechanisms involved in SCA8, we developed a mouse model in which Klhl1 is deleted in either all tissues or is deleted specifically in Purkinje cells only. We found that mice that are either homozygous or heterozygous for the Klhl1 deletion have significant gait abnormalities at an early age and develop a significant loss of motor coordination by 24 weeks of age. This loss progresses more rapidly in homozygous knock-outs. Mice with Klhl1 specifically deleted in only Purkinje cells had a loss of motor coordination that was almost identical to the total-tissue deletion mice. Finally, we found significant Purkinje cell dendritic deficits, as measured by the thickness of the molecular layer, in all mice in which Klhl1 was deleted (both total and Purkinje cell-specific deletions) and an intermediate reduction in molecular layer thickness in mice with reduced levels of Klhl1 expression (heterozygous deletions). The results from this mouse model show that even a partial loss of Klhl1 function leads to degeneration of Purkinje cell function and indicates that loss of KLHL1 activity is likely to play a significant part in the underlying pathophysiology of SCA8.

Bidirectional expression of CUG and CAG expansion transcripts and intranuclear polyglutamine inclusions in spinocerebellar ataxia type 8

We previously reported that a (CTG)n expansion causes spinocerebellar ataxia type 8 (SCA8), a slowly progressive ataxia with reduced penetrance. We now report a transgenic mouse model in which the full-length human SCA8 mutation is transcribed using its endogenous promoter. (CTG)116 expansion, but not (CTG)11 control lines, develop a progressive neurological phenotype with in vivo imaging showing reduced cerebellar-cortical inhibition. 1C2-positive intranuclear inclusions in cerebellar Purkinje and brainstem neurons in SCA8 expansion mice and human SCA8 autopsy tissue result from translation of a polyglutamine protein, encoded on a previously unidentified antiparallel transcript (ataxin 8, ATXN8) spanning the repeat in the CAG direction. The neurological phenotype in SCA8 BAC expansion but not BAC control lines demonstrates the pathogenicity of the (CTG-CAG)n expansion. Moreover, the expression of noncoding (CUG)n expansion transcripts (ataxin 8 opposite strand, ATXN8OS) and the discovery of intranuclear polyglutamine inclusions suggests SCA8 pathogenesis involves toxic gain-of-function mechanisms at both the protein and RNA levels.

C-termini of P/Q-type Ca2+ channel alpha1A subunits translocate to nuclei and promote polyglutamine-mediated toxicity

P/Q-type voltage-gated calcium channels are regulated, in part, through the cytoplasmic C-terminus of their alpha1A subunit. Genetic absence or alteration of the C-terminus leads to abnormal channel function and neurological disease. Here, we show that the terminal 60-75 kDa of the endogenous alpha1A C-terminus is cleaved from the full-length protein and is present in cell nuclei. Antiserum to the C-terminus (CT-2) labels both wild-type mouse and human Purkinje cell nuclei, but not leaner mouse cerebellum. Human embryonic kidney cells stably expressing beta3 and alpha2delta subunits and transiently transfected with full-length human alpha1A contain a 75 kDa CT-2 reactive peptide in their nuclear fraction. Primary granule cells transfected with C-terminally Green fluorescent protein (GFP)-tagged alpha1A exhibit GFP nuclear labeling. Nuclear translocation depends partly on the presence of three nuclear localization signals within the C-terminus. The C-terminal fragment bears a polyglutamine tract which, when expanded (Q33) as in spinocerebellar ataxia type 6 (SCA6), is toxic to cells. Moreover, polyglutamine-mediated toxicity is dependent on nuclear localization. Finally, in the absence of flanking sequence, the Q33 expansion alone does not kill cells. These results suggest a novel processing of the P/Q-type calcium channel and a potential mechanism for the pathogenesis of SCA6.

Spectrin mutations cause spinocerebellar ataxia type 5

We have discovered that beta-III spectrin (SPTBN2) mutations cause spinocerebellar ataxia type 5 (SCA5) in an 11-generation American kindred descended from President Lincoln's grandparents and two additional families. Two families have separate in-frame deletions of 39 and 15 bp, and a third family has a mutation in the actin/ARP1 binding region. Beta-III spectrin is highly expressed in Purkinje cells and has been shown to stabilize the glutamate transporter EAAT4 at the surface of the plasma membrane. We found marked differences in EAAT4 and GluRdelta2 by protein blot and cell fractionation in SCA5 autopsy tissue. Cell culture studies demonstrate that wild-type but not mutant beta-III spectrin stabilizes EAAT4 at the plasma membrane. Spectrin mutations are a previously unknown cause of ataxia and neurodegenerative disease that affect membrane proteins involved in glutamate signaling.

Clinical and pathologic evidence of corticobasal degeneration and progressive supranuclear palsy in familial tauopathy

BACKGROUND

Corticobasal degeneration (CBD) and progressive supranuclear palsy (PSP) are neurodegenerative tauopathies. Sporadic and familial cases of PSP and CBD have been noted, but both have not been reported in a single family.

OBJECTIVE

To describe the clinical, oculomotor, balance, functional imaging, histopathologic, and genetic studies in a family with CBD and PSP.

DESIGN

A report of the clinical and pathological features in a familial tauopathy.

SETTING

University of Minnesota. Patients We evaluated 2 siblings and clinically assessed 20 additional family members.

MAIN OUTCOME MEASURES

Demonstration of salient features in deceased and living family members.

RESULTS

Histopathologically confirmed CBD in one sibling and PSP in another deceased sibling were demonstrated; both had clinical features of corticobasal syndrome. In addition, 3 siblings had probable PSP by clinical criteria. Genetic studies of 4 affected family members demonstrated the H1/H1 haplotype but did not reveal pathogenic tau mutations. The family history revealed consanguinity.

CONCLUSIONS

This is the first report, to our knowledge, of CBD and PSP in 2 individuals in a single family who presented with corticobasal syndrome and had other affected siblings with clinical PSP. Despite clinical and pathologic heterogeneity, a unifying genetic etiology appears likely in this familial tauopathy.