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Dopamine agonist withdrawal syndrome (DAWS) results from the reduction or suspension of dopamine agonist medications; it encompasses mainly psychiatric symptoms, including suicidal behaviors. In patients with Parkinson's disease (PD), the impact of DAWS can be significant in terms of distress and disability; however, we must take this syndrome into account as a threatening condition because suicidal behaviors could be developing in the context of DAWS. Here we present a brief case of DAWS affecting a young man with PD, whom abruptly discontinued DA treatment and developed psychiatric symptoms within two weeks which led to a suicidal attempt.

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INTRODUCTION: Mutations in presenilin-1 (PSEN1) account for the majority of cases of familial autosomal dominant early-onset Alzheimer's disease (AD) as well as in sporadic forms. Atypical presentations are reported including extrapyramidal signs. In the last years, a pleiotropic effect of some PSEN1 variants has been reported in Parkinson's disease (PD). OBJECTIVE: to report a new PSEN1 mutation characterized by early-onset Parkinsonism (EOPD) without dementia or classical AD biomarkers phenotype. PATIENT AND METHODS: An Argentinian 46 years old woman was diagnosed with EOPD at 35 years old with no family history of neurodegenerative disorders. Her medical history included iron deficiency and anemia since childhood. A brain MRI showed moderate frontal atrophy. 18FDG-PET and PiB-PET as well as CSF biomarkers were inconclusive for AD. Two neuropsychological examinations were compatible with a mild non amnestic cognitive impairment. Whole blood DNA was extracted and whole exome sequencing and analysis was performed. RESULTS AND CONCLUSION: A heterozygous novel missense PSEN1 mutation (position 14:73637540, A > T, pArg41Ser) was identified as a likely causative mutation in this patient. To the best of our knowledge, this case is the first PSEN1 mutation with a l-dopa responsive Parkinsonism lacking distinctive classical AD biomarkers. This case opens a new window to explore the pathophysiological link among PSEN1 and EOPDs and contributes to increase the phenotypes of PSEN1 variants.

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Several epidemiological studies support low cancer rates in patients with neurodegenerative disorders, including Parkinson's disease, Huntington's disease, and Alzheimer's disease. Different mechanisms were raised as possible causes, from mutated tumor suppressor genes (PARKIN, PINK1) to small interfering RNA based on the CAG trinucleotide repeat expansions located in introns or untranslated regions. However, as every rule has an exception, some tumors have an increased incidence in these neurodegenerative diseases such as breast and skin cancer (melanoma). This mini-review aims to establish the epidemiology between these neurodegenerative disorders and cancer to determine the possible mechanisms involved and therefore set eventual therapeutic applications. According to our findings, we conclude the presence of an inverse relationship among most cancers and the aforementioned neurodegenerative disorders. However, this concept needs to be considered cautiously considering specific genetic and extra-genetic linkage factors for particular tumors.

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Huntington disease (HD) is a devastating monogenic autosomal dominant disorder. HD is caused by a CAG expansion in exon 1 of the gene coding for huntingtin, placed in the short arm of chromosome 4. Despite its well-defined genetic origin, the molecular and cellular mechanisms underlying the disease are unclear and complex. Here, we review some of the currently known functions of the wild-type huntingtin protein and discuss the deleterious effects that arise from the expansion of the CAG repeats, which are translated into an abnormally long polyglutamine tract. Also, we present a modern view on the molecular biology of HD as a representative of the group of polyglutamine diseases, with an emphasis on conformational changes of mutant huntingtin, disturbances in its cellular processing, and proteolytic stress in degenerating neurons. The main pathogenetic mechanisms of neurodegeneration in HD are discussed in detail, such as autophagy, impaired mitochondrial biogenesis, lysosomal dysfunction, organelle and protein transport, inflammation, oxidative stress, and transcription factor modulation. However, other unraveling mechanisms are still unknown. This practical and brief review summarizes some of the currently known functions of the wild-type huntingtin protein and the recent findings related to the mechanisms involved in HD pathogenesis.

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BACKGROUND: Huntington's disease (HD) is a neurodegenerative disorder that includes motor, psychiatric and cognitive manifestations with typical onset of symptoms is in the forties. A percentage of patients (4.4% - 11.5%) may be exceptions to this and manifest symptoms later (>60 years old). Diagnosis of Late onset HD (LoHD) can be a challenge, due to the low suspicion of the disease at this age. OBJECTIVE: To review the genotype and phenotype of LoHD in an Argentinian cohort. METHODS: We reviewed the medical records and genetic testing of a total of 95 individuals with clinical and molecular diagnosis of Huntington's disease, based on 2 institution's registry. RESULTS: Among our HD cohort, 10 patients (10.52%) had LoHD, with variable results regarding family history. The average of repetitions of the expanded allele was 40 (range 38-44). All cases had mild motor symptoms at onset. CONCLUSIONS: Late onset HD can be a diagnostic challenge, due to its slow progression, unawareness of manifestations among patients and in many cases, mild symptomatology that does not warrant medical attention.

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Background: Holmes tremor is a rare symptomatic movement disorder, characterized by a combination of resting, postural, and intention tremor. It is usually caused by lesions in the brainstem, thalamus, and cerebellum. Despite pharmacological advances, its treatment remains a challenge; many medications have been used with various degrees of effectiveness. Stereotactic thalamotomy and deep brain stimulation in the ventralis intermedius nucleus have been effective surgical procedures in cases refractory to medical treatment. Case Report: Here we report a young woman with topiramate-responsive Holmes tremor secondary to a brainstem cavernoma. Discussion: Herein we report a Holmes tremor responsive to Topiramate.

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