Project description:To characterize the clinical features and neuropathology associated with recessive VAC14 mutations.Whole-exome sequencing was used to identify the genetic etiology of a rapidly progressive neurological disease presenting in early childhood in two deceased siblings with distinct neuropathological features on post mortem examination.We identified compound heterozygous variants in VAC14 in two deceased siblings with early childhood onset of severe, progressive dystonia, and neurodegeneration. Their clinical phenotype is consistent with the VAC14-related childhood-onset, striatonigral degeneration recently described in two unrelated children. Post mortem examination demonstrated prominent vacuolation associated with degenerating neurons in the caudate nucleus, putamen, and globus pallidus, similar to previously reported ex vivo vacuoles seen in the late-endosome/lysosome of VAC14-deficient neurons. We identified upregulation of ubiquitinated granules within the cell cytoplasm and lysosomal-associated membrane protein (LAMP2) around the vacuole edge to suggest a process of vacuolation of lysosomal structures associated with active autophagocytic-associated neuronal degeneration.Our findings reveal a distinct clinicopathological phenotype associated with recessive VAC14 mutations.
Project description:Chorea hyperglycemia basal ganglia (CHBG) syndrome is an uncommon manifestation of diabetes seen in patients with poor glycemic control. It is characterized by sudden onset of chorea with characteristic hyperintensities of the basal ganglia on brain magnetic resonance imaging. We report a case of a 31-year-old female patient with a history of type 1 diabetes mellitus, renal failure, and hypertension, who presented with acute symptoms of chorea involving both the upper and lower limbs with facial and cervical dystonia. Magnetic resonance imaging revealed bilateral hyperintensities of the globus pallidus and putamen. Control of blood glucose levels led to resolution of the choreic movements. In addition, follow-up magnetic resonance imaging studies revealed improvement in the hyperintensities of the basal ganglia bilaterally.
Project description:Chorea is a hyperkinetic movement disorder resulting from dysfunction of striatal medium spiny neurons (MSNs), which form the main output projections from the basal ganglia. Here, we used whole-exome sequencing to unravel the underlying genetic cause in three unrelated individuals with a very similar and unique clinical presentation of childhood-onset chorea and characteristic brain MRI showing symmetrical bilateral striatal lesions. All individuals were identified to carry a de novo heterozygous mutation in PDE10A (c.898T>C [p.Phe300Leu] in two individuals and c.1000T>C [p.Phe334Leu] in one individual), encoding a phosphodiesterase highly and selectively present in MSNs. PDE10A contributes to the regulation of the intracellular levels of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). Both substitutions affect highly conserved amino acids located in the regulatory GAF-B domain, which, by binding to cAMP, stimulates the activity of the PDE10A catalytic domain. In silico modeling showed that the altered residues are located deep in the binding pocket, where they are likely to alter cAMP binding properties. In vitro functional studies showed that neither substitution affects the basal PDE10A activity, but they severely disrupt the stimulatory effect mediated by cAMP binding to the GAF-B domain. The identification of PDE10A mutations as a cause of chorea further motivates the study of cAMP signaling in MSNs and highlights the crucial role of striatal cAMP signaling in the regulation of basal ganglia circuitry. Pharmacological modulation of this pathway could offer promising etiologically targeted treatments for chorea and other hyperkinetic movement disorders.
Project description:Oxidative phosphorylation dysfunction has been found in many different disorders. This biochemical pathway depends on mitochondrial protein synthesis. Thus, mutations in components of the mitochondrial translation system can be responsible for some of these pathologies. We identified a new homozygous missense mutation in the mitochondrial translation elongation factor Ts gene in a patient suffering from slowly progressive childhood ataxia and hypertrophic cardiomyopathy. Using cell, biochemical and molecular-genetic protocols, we confirm it as the etiologic factor of this phenotype. Moreover, as an important functional confirmation, we rescued the normal molecular phenotype by expression of the wild-type TSFM cDNA in patient's fibroblasts. Different TSFM mutations can produce the same or very different clinical phenotypes, going from abortions to moderately severe presentations. On the other hand, the same TSFM mutation can also produce same or different phenotypes within the same range of presentations, therefore suggesting the involvement of unknown factors.
Project description:BackgroundThe neural basis of timing remains poorly understood. Although controversy persists, many lines of evidence, including studies in animals, functional imaging studies in humans and lesion studies in humans and animals suggest that the basal ganglia are important for temporal processing [1].Methodology/principal findingsWe report data from a wide range of timing tasks from two subjects with disabling neurologic deficits caused by bilateral lesions of the basal ganglia. Both subjects perform well on tasks assessing time estimation, reproduction and production tasks. Additionally, one subject performed normally on psychophysical tasks requiring the comparison of time intervals ranging from milliseconds to seconds; the second subject performed abnormally on the psychophysical task with a 300ms standard but did well with 600ms, 2000ms and 8000ms standards. Both subjects performed poorly on an isochronous rhythm production task on which they are required to maintain rhythmic tapping.Conclusions/significanceAs studies of subjects with brain lesions permit strong inferences regarding the necessity of brain structures, these data demonstrate that the basal ganglia are not crucial for many sub- or supra-second timing operations in humans but are needed for the timing procedures that underlie the production of movements. This dissociation suggests that distinct and dissociable processes may be employed to measure time intervals. Inconsistencies in findings regarding the neural basis of timing may reflect the availability of multiple temporal processing routines that are flexibly implemented in response to task demands.
Project description:Isolated hemichorea (HC) in adults has a relatively restricted differential diagnosis including stroke of contralateral basal ganglia nuclei, nonketotic hyperglycemia, and basal ganglia toxoplasmosis in HIV infection. Hypoparathyroidism-related basal ganglia calcification can potentially cause neurological problems, including movement disorders, that are usually bilateral in keeping with bilateral symmetric lesions. We report a patient with video-documented isolated, adult-onset HC due to iatrogenic hypoparathyroidism and bilateral basal ganglia calcification. A 47-year-old woman presented with isolated adult-onset HC of 2 years' duration as the presenting and only neurological feature of hypoparathyroidism and bilateral extensive basal ganglia calcification, 20 years after thyroidectomy-induced hypoparathyroidism. Significant improvement in the unilateral hyperkinesia was noted after correction of hypocalcemia and hypoparathyroidism at 3 months. Isolated HC in adults is a rare presenting feature of hypoparathyroidism with bilateral basal ganglia calcification and is treatable with correction of the underlying metabolic abnormality. In all cases with a movement disorder and brain calcification, hypoparathyroidism should be actively sought as this treatable condition must not be missed.
Project description:BACKGROUND:Dilated cardiomyopathy (DCM), non-progressive cerebellar ataxia (A), testicular dysgenesis, growth failure, and 3-methylglutaconic aciduria are the hallmarks of DNAJC19 defect (or DCMA syndrome) due to biallelic mutations in DNAJC19. To date DCMA syndrome has been reported in 19 patients from Canada and in two Finnish siblings. The underlying pathomechanism is unknown; however, DNAJC19 is presumed to be involved in mitochondrial membrane related processes (e.g., protein import and cardiolipin remodeling). Here, we report an additional patient with progressive cerebellar atrophy and white matter changes. PATIENT AND METHODS:A Turkish boy presented at age 2 months with dilated cardiomyopathy (initially worsening then stabilizing in the second year of life), growth failure, bilateral cryptorchidism, and facial dysmorphism. Mental and motor developmental were, respectively, moderately and severely delayed. Profound intentional tremor and dyskinesia, spasticity (particularly at the lower extremities), and dystonia were observed. Sensorineural hearing loss was also diagnosed. MRI showed bilateral basal ganglia signal alterations. Plasma lactate levels were increased, as was urinary excretion of 3-methylglutaconic acid. He deceased aged 3 years. RESULTS:Sanger Sequencing of DNAJC19 confirmed the clinical diagnosis of DNAJC19 defect by revealing the previously unreported homozygous stop mutation c.63delC (p.Tyr21*). Investigation of enzymes of mitochondrial energy metabolism revealed decreased activity of cytochrome c oxidase in muscle tissue. DISCUSSION:Sensorineural hearing loss and bilateral basal ganglia lesions are common symptoms of mitochondrial disorders. This is the first report of an association with DNAJC19 defect.