Federica Zibordi

Iron-related MRI images in patients with pantothenate kinase-associated neurodegeneration (PKAN) treated with deferiprone: Results of a phase II pilot trial

The safety and efficacy of the oral iron‐chelating agent deferiprone on magnetic resonance pallida iron concentration and on clinical status were investigated in 10 patients affected by pantothenate kinase–associated neurodegeneration.

Metabolic consequences of mitochondrial coenzyme A deficiency in patients with PANK2 mutations.

Pantothenate kinase-associated neurodegeneration (PKAN) is a rare, inborn error of metabolism characterized by iron accumulation in the basal ganglia and by the presence of dystonia, dysarthria, and retinal degeneration. Mutations in pantothenate kinase 2 (PANK2), the rate-limiting enzyme in mitochondrial coenzyme A biosynthesis, represent the most common genetic cause of this disorder. How mutations in this core metabolic enzyme give rise to such a broad clinical spectrum of pathology remains a mystery. To systematically explore its pathogenesis, we performed global metabolic profiling on plasma from a cohort of 14 genetically defined patients and 18 controls. Notably, lactate is elevated in PKAN patients, suggesting dysfunctional mitochondrial metabolism. As predicted, but never previously reported, pantothenate levels are higher in patients with premature stop mutations in PANK2. Global metabolic profiling and follow-up studies in patient-derived fibroblasts also reveal defects in bile acid conjugation and lipid metabolism, pathways that require coenzyme A. These findings raise a novel therapeutic hypothesis, namely, that dietary fats and bile acid supplements may hold potential as disease-modifying interventions. Our study illustrates the value of metabolic profiling as a tool for systematically exploring the biochemical basis of inherited metabolic diseases.

Myoclonus–dystonia syndrome: Clinical presentation, disease course, and genetic features in 11 families

Myoclonus–dystonia syndrome (MDS) is an inherited movement disorder with clinical and genetic heterogeneity. The epsilon sarcoglycan (SGCE) gene is an important cause of MDS. We report the results of a clinical and genetic study of 20 patients from 11 families. We disclosed six novel and two previously described mutations in nine families. The majority of patients had a phenotype of myoclonus and dystonia in combination, but clinical findings considered atypical, such a very early onset, distal myoclonus, and legs involvement, were detected in a significant proportion of cases. The disease course was variable, from progression to spontaneous remission of the motor symptoms. There were no obvious differences between mutation‐positive and ‐negative cases.

A neurophysiological study of myoclonus in patients with DYT11 myoclonus-dystonia syndrome

Mutations in the ϵ‐sarcoglycan (SGCE) gene have been associated with DYT11 myoclonus‐dystonia syndrome (MDS). The aim of this study was to characterize myoclonus in 9 patients with DYT11‐MDS presenting with predominant myoclonus and mild dystonia by means of neurophysiological techniques. Variously severe multifocal myoclonus occurred in all of the patients, and included short (mean 89.1 ± 13.3 milliseconds) electromyographic bursts without any electroencephalographic correlate, sometimes presenting a pseudo‐rhythmic course. Massive jerks could be evoked by sudden stimuli in 5 patients, showing a “startle‐like” muscle spreading and latencies consistent with a brainstem origin. Somatosensory evoked potentials and long‐loop reflexes were normal, as was silent period and long‐term intracortical inhibition evaluated by means of transcranial magnetic stimulation; however, short‐term intracortical inhibition revealed subtle impairment, and event‐related synchronization (ERS) in the beta band was delayed. Blink reflex recovery was strongly enhanced. Myoclonus in DYT11‐MDS seems to be generated at subcortical level, and possibly involves basal ganglia and brainstem circuitries. Cortical impairment may depend from subcortical dysfunction, but it can also have a role in influencing the myoclonic presentation. The wide distribution of the defective SCGE in DYT11‐MDS may justify the involvement of different brain areas.

C19orf12 and FA2H Mutations Are Rare in Italian Patients With Neurodegeneration With Brain Iron Accumulation

Neurodegeneration with brain iron accumulation (NBIA) defines a wide spectrum of clinical entities characterized by iron accumulation in specific regions of the brain, predominantly in the basal ganglia. We evaluated the presence of FA2H and C19orf12 mutations in a cohort of 46 Italian patients with early onset NBIA, which were negative for mutations in the PANK2 and PLA2G6 genes. Follow-up molecular genetic and in vitro analyses were then performed. We did not find any mutations in the FA2H gene, although we identified 3 patients carrying novel mutations in the C19orf12 gene. The recent discovery of new genes responsible for NBIA extends the spectrum of the genetic investigation now available for these disorders and makes it possible to delineate a clearer clinical-genetic classification of different forms of this syndrome. A large fraction of patients still remain without a molecular genetics diagnosis, suggesting that additional NBIA genes are still to be discovered.

Phenomenology of psychogenic movement disorders in children.

Psychogenic movement disorders are heterogeneous and diagnostically challenging. Despite the growing literature on adult forms, clinical features in children have received relatively little attention. We retrospectively reviewed medical records and video of patients <18 years diagnosed with a psychogenic movement disorder at our institute between 2007 and 2010. We identified 14 patients (6 males and 8 females) with a mean onset age of 11.5 years. Levels of diagnostic confidence were documented (2 patients), clinically established (8 patients), and probable (4 patients). A single movement disorder was present in 10 patients (71%); 4 patients (29%) presented an association of two or more movement disorders. Eleven patients presented other medically unexplained symptoms associated with their movement disorders. Five patients, among 6 with chronic occurrence, performed a polymyographic study showing significant modifications of frequency, amplitude, and distribution of electromyographic activity, related to distracting maneuvers. The present series represents 5% of all movement disorders observed in the considered period and 32% of nonorganic neurological manifestations. The most frequent movement disorders were tremor (36%) and dystonia (29%). We describe two phenotypes not previously reported among psychogenic movement disorders: myoclonus and association of myoclonus with dystonia. We remark on the presence of psychogenic symptoms associated with movement disorders (79%) as being one of the most useful clinical clues as well as on the value of polymyographic study in chronic psychogenic movement disorders, which provide evidence of the inconsistency of movement disorders.

Variant late infantile ceroid lipofuscinoses associated with novel mutations in CLN6

The neuronal ceroid lipofuscinoses (NCL) are heterogeneous neurodegenerative disorders with typical autofluorescence material stored in tissues. Ten clinical NCL forms and eight causative genes are known. Mutations in CLN6 have been reported in roughly 30 patients, mostly in association with the variant late-infantile NCL (v-LINCL) phenotype. We screened CLN6 in 30 children from a cohort of 53 v-LINCL cases and revised their clinical and ultrastructural features. We detected 11 mutations, eight of which are novel, all predicting a direct impairing of the putative gene function. No clear-cut genotype-phenotype correlations were observed, with inter- and intra-familial variability evident for few recurrent mutations. Ultrastructural findings were suggestive of an impaired regulation of the autophagic vacuoles turnover. While expanding the array of CLN6 mutations, we showed that more than half of our v-LINCL cases lack a DNA confirmation and further molecular etiologies are to be searched.

ADCY5-related movement disorders: Frequency, disease course and phenotypic variability in a cohort of paediatric patients

Introduction ADCY5 mutations have been recently identified as an important cause of early-onset hyperkinetic movement disorders. The phenotypic spectrum associated with mutations in this gene is expanding. However, the ADCY5 mutational frequency in cohorts of paediatric patients with hyperkinetic movement disorders has not been evaluated. Methods We performed a screening of the entire ADCY5 coding sequence in 44 unrelated subjects with genetically undiagnosed childhood-onset hyperkinetic movement disorders, featuring chorea alone or in combination with myoclonus and dystonia. All patients had normal CSF analysis and brain imaging and were regularly followed-up in tertiary centers for paediatric movement disorders. Results We identified five unrelated subjects with ADCY5 mutations (11% of the cohort). Three carried the p. R418W mutation, one the p. R418Q and one the p. R418G mutation. Mutations arose de novo in four cases, while one patient inherited the mutation from his similarly affected father. All patients had delayed motor and/or language milestones with or without axial hypotonia and showed generalized chorea and dystonia, with prominent myoclonic jerks in one case. Episodic exacerbations of the baseline movement disorder were observed in most cases, being the first disease manifestation in two patients. The disease course was variable, from stability to spontaneous improvement during adolescence. Conclusion Mutations in ADCY5 are responsible for a hyperkinetic movement disorder that can be preceded by episodic attacks before the movement disorder becomes persistent and is frequently misdiagnosed as dyskinetic cerebral palsy. A residual degree of neck hypotonia and a myopathy-like facial appearance are frequently observed in patients with ADCY5 mutations.

Neurological Disorders Associated with Striatal Lesions: Classification and Diagnostic Approach

Neostriatal abnormalities can be observed in a very large number of neurological conditions clinically dominated by the presence of movement disorders. The neuroradiological picture in some cases has been described as “bilateral striatal necrosis” (BSN). BSN represents a condition histo-pathologically defined by the involvement of the neostriata and characterized by initial swelling of putamina and caudates followed by degeneration and cellular necrosis. After the first description in 1975, numerous acquired and hereditary conditions have been associated with the presence of BSN. At the same time, a large number of disorders involving neostriata have been described as BSN, in some cases irrespective of the presence of signs of cavitation on MRI. As a consequence, the etiological spectrum and the nosographic boundaries of the syndrome have progressively become less clear. In this study, we review the clinical and radiological features of the conditions associated with MRI evidence of bilateral striatal lesions. Based on MRI findings, we have distinguished two groups of disorders: BSN and other neostriatal lesions (SL). This distinction is extremely helpful in narrowing the differential diagnosis to a small group of known conditions. The clinical picture and complementary exams will finally lead to the diagnosis. We provide an update on the etiological spectrum of BSN and propose a diagnostic flowchart for clinicians.

Early onset primary dystonia

Dystonia is a syndrome characterized by sustained muscle contractions, frequently causing twisting and repetitive movements or abnormal postures. It is classified by age at onset, by distribution, and by aetiology. The aetiological classification distinguishes the following categories: primary, dystonia plus, secondary, heredo-degenerative and psychogenic dystonia. Primary dystonia is defined as clinical condition characterized by dystonia as the only neurological abnormality apart from tremor. Different genetic alterations and gene loci have been mapped in familial and sporadic patients. Early onset-primary dystonia (EO-PD) is the most severe form of primary dystonia, with clinical and genetic heterogeneity. It usually starts in one body part, subsequently spreads to involve other body regions with frequent generalization. DYT1 dystonia is transmitted as an autosomal dominant trait with reduced penetrance. The unique underlying mutation is a GAG deletion in the coding region of the TOR1A gene, located at chromosome 9q34. DYT16 dystonia is a novel recessive form of EO-PD, recently described in few patients, caused by mutations in the PRKRA gene located at chromosome 2q31. At least other two loci have been mapped, but there remains a large number of patients with EO-PD in whom no genetic alteration is discovered.