LRP10 genetic variants in familial Parkinson's disease and dementia with Lewy bodies: a genome-wide linkage and sequencing study.

BACKGROUND: Most patients with Parkinson's disease, Parkinson's disease dementia, and dementia with Lewy bodies do not carry mutations in known disease-causing genes. The aim of this study was to identify a novel gene implicated in the development of these disorders. METHODS: Our study was done in three stages. First, we did genome-wide linkage analysis of an Italian family with dominantly inherited Parkinson's disease to identify the disease locus. Second, we sequenced the candidate gene in an international multicentre series of unrelated probands who were diagnosed either clinically or pathologically with Parkinson's disease, Parkinson's disease dementia, or dementia with Lewy bodies. As a control, we used gene sequencing data from individuals with abdominal aortic aneurysms (who were not examined neurologically). Third, we enrolled an independent series of patients diagnosed clinically with Parkinson's disease and controls with no signs or family history of Parkinson's disease, Parkinson's disease dementia, or dementia with Lewy bodies from centres in Portugal, Sardinia, and Taiwan, and screened them for specific variants. We also did mRNA and brain pathology studies in three patients from the international multicentre series carrying disease-associated variants, and we did functional protein studies in in-vitro models, including neurons from induced pluripotent stem-like cells. FINDINGS: Molecular studies were done between Jan 1, 2008, and Dec 31, 2017. In the initial kindred of ten affected Italian individuals (mean age of disease onset 59·8 years [SD 8·7]), we detected significant linkage of Parkinson's disease to chromosome 14 and nominated LRP10 as the disease-causing gene. Among the international series of 660 probands, we identified eight individuals (four with Parkinson's disease, two with Parkinson's disease dementia, and two with dementia with Lewy bodies) who carried different, rare, potentially pathogenic LRP10 variants; one carrier was found among 645 controls with abdominal aortic aneurysms. In the independent series, two of these eight variants were detected in three additional Parkinson's disease probands (two from Sardinia and one from Taiwan) but in none of the controls. Of the 11 probands from the international and independent cohorts with LRP10 variants, ten had a positive family history of disease and DNA was available from ten affected relatives (in seven of these families). The LRP10 variants were present in nine of these ten relatives, providing independent-albeit limited-evidence of co-segregation with disease. Post-mortem studies in three patients carrying distinct LRP10 variants showed severe Lewy body pathology. Of nine variants identified in total (one in the initial family and eight in stage 2), three severely affected LRP10 expression and mRNA stability (1424+5delG, 1424+5G→A, and Ala212Serfs*17, shown by cDNA analysis), four affected protein stability (Tyr307Asn, Gly603Arg, Arg235Cys, and Pro699Ser, shown by cycloheximide-chase experiments), and two affected protein localisation (Asn517del and Arg533Leu; shown by immunocytochemistry), pointing to loss of LRP10 function as a common pathogenic mechanism. INTERPRETATION: Our findings implicate LRP10 gene defects in the development of inherited forms of α-synucleinopathies. Future elucidation of the function of the LRP10 protein and pathways could offer novel insights into mechanisms, biomarkers, and therapeutic targets. FUNDING: Stichting ParkinsonFonds, Dorpmans-Wigmans Stichting, Erasmus Medical Center, ZonMw-Memorabel programme, EU Joint Programme Neurodegenerative Disease Research (JPND), Parkinson's UK, Avtal om Läkarutbildning och Forskning (ALF) and Parkinsonfonden (Sweden), Lijf and Leven foundation, and cross-border grant of Alzheimer Netherlands-Ligue Européene Contre la Maladie d'Alzheimer (LECMA).

GIGYF2 mutations are not a frequent cause of familial Parkinson's disease.

Mutations in the Grb10-interacting GYF protein 2 (GIGYF2) gene, within the PARK11 locus, have been nominated as a cause of Parkinson's disease in Italian and French populations. By sequencing the whole GIGYF2 coding region in forty-six probands (thirty-seven Italians) with familial Parkinson's disease compatible with an autosomal dominant inheritance, we identified no mutations. Our data add to a growing body of evidence suggesting that GIGYF2 mutations are not a frequent cause of PD.

High prevalence of extrapyramidal signs and symptoms in a group of Italian dental technicians.

BACKGROUND: Occupational and chronic exposure to solvents and metals is considered a possible risk factor for Parkinson's disease and essential tremor. While manufacturing dental prostheses, dental technicians are exposed to numerous chemicals that contain toxins known to affect the central nervous system, such as solvents (which contain n-hexane in particular) and metals (which contain mercury, iron, chromium, cobalt and nickel). METHODS: We performed an epidemiological and clinical study on all 27 dental technicians working in a school for dental technicians. We asked all the technicians to fill in a self-administered questionnaire on extrapyramidal symptoms, and the General Health Questionnaire (GHQ), a self-administered screening instrument, to detect any psychiatric disorders. Moreover, we invited all 27 dental technicians to undergo a neurological examination and provide a detailed occupational history in our clinic. RESULTS: Of the 14 subjects who underwent the neurological examination, four had postural tremor and one had a diagnosis of Parkinson's disease. CONCLUSION: We found a high prevalence of extrapyramidal signs and symptoms in this group of male dental technicians working in a state technical high school in Rome. We believe that this finding may be due to the presence of toxins in the dental technician's work.

Levetiracetam in tardive dyskinesia.

OBJECTIVES: The aim of this study was to evaluate the effect of levetiracetam on tardive dyskinesia (TD), which is known to be a major limitation of chronic antipsychotic drug therapy, particularly with conventional antipsychotics. METHODS: Sixteen patients suffering from chronic psychosis with TD were enrolled consecutively. Levetiracetam was given in gradually increasing doses, starting with 125 twice a day until the best clinical benefit was achieved (mean dosage, 2,290 mg; range, 1,000-3,000 mg). Tardive dyskinesia was assessed using the Abnormal Involuntary Movement Scale at baseline and after 1 month and 3 months of treatment with levetiracetam. RESULTS: Compared with baseline, there was a significant improvement in the Abnormal Involuntary Movement Scale score after 1 month still present after 3 months (P < 0.001). All patients well tolerated levetiracetam, except one who dropped out of the trial after the first 2 weeks owing to excessive drowsiness. CONCLUSIONS: The results of this open-label observational study suggest that levetiracetam is a well-tolerated drug and effectively controls TD.

A frequent LRRK2 gene mutation associated with autosomal dominant Parkinson's disease.

Mutations in the LRRK2 gene have been identified in families with autosomal dominant parkinsonism. We amplified and sequenced the coding region of LRRK2 from genomic DNA by PCR, and identified a heterozygous mutation (Gly2019 ser) present in four of 61 (6.6%) unrelated families with Parkinson's disease and autosomal dominant inheritance. The families originated from Italy, Portugal, and Brazil, indicating the presence of the mutation in different populations. The associated phenotype was broad, including early and late disease onset. These findings confirm the association of LRRK2 with neurodegeneration, and identify a common mutation associated with dominantly inherited Parkinson's disease.

Mirtazapine in L-dopa-induced dyskinesias.

Mirtazapine is a novel antidepressant with a pharmacologic profile (alpha-2 antagonist, 5HT-(1A) agonist, and 5HT-(2) antagonist) that renders it potentially useful for l-dopa-induced dyskinesias. Drugs with 5HT-(1A) agonistic activity, such as buspirone and tandospirone, have been reported to be effective in reducing l-dopa-induced dyskinesias. Furthermore, 5HT-(2) antagonism may, by reducing substantia nigra pars reticulata hyperactivity, play a role in the improvement of Parkinsonian symptoms and l-dopa-induced dyskinesias, as has been observed with ritanserin, a 5HT-(2) antagonist. Alpha-2 antagonists, such as idazoxan, have recently also been reported to improve l-dopa-induced dyskinesias. The authors investigated the antidyskinetic properties of mirtazapine by designing an open-label study of 20 Parkinsonian patients with l-dopa-induced dyskinesias. Mirtazapine proved to be moderately effective in reducing l-dopa-induced dyskinesias, either alone or in association with amantadine. Mirtazapine may be of use in patients who do not respond or are intolerant to amantadine.