X-Chromosome Association Study in Latin American Cohorts Identifies New Loci in Parkinson's Disease.

BACKGROUND: Sex differences in Parkinson's disease (PD) risk are well-known. However, the role of sex chromosomes in the development and progression of PD is still unclear. OBJECTIVE: The objective of this study was to perform the first X-chromosome-wide association study for PD risk in a Latin American cohort. METHODS: We used data from three admixed cohorts: (1) Latin American Research consortium on the Genetics of Parkinson's Disease (n = 1504) as discover cohort, and (2) Latino cohort from International Parkinson Disease Genomics Consortium (n = 155) and (3) Bambui Aging cohort (n = 1442) as replication cohorts. We also developed an X-chromosome framework specifically designed for admixed populations. RESULTS: We identified eight linkage disequilibrium regions associated with PD. We replicated one of these regions (top variant rs525496; discovery odds ratio [95% confidence interval]: 0.60 [0.478-0.77], P = 3.13 × 10-5 replication odds ratio: 0.60 [0.37-0.98], P = 0.04). rs5525496 is associated with multiple expression quantitative trait loci in brain and non-brain tissues, including RAB9B, H2BFM, TSMB15B, and GLRA4, but colocalization analysis suggests that rs5525496 may not mediate risk by expression of these genes. We also replicated a previous X-chromosome-wide association study finding (rs28602900), showing that this variant is associated with PD in non-European populations. CONCLUSIONS: Our results reinforce the importance of including X-chromosome and diverse populations in genetic studies. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Characterizing the Genetic Architecture of Parkinson's Disease in Latinos.

OBJECTIVE: This work was undertaken in order to identify Parkinson's disease (PD) risk variants in a Latino cohort, to describe the overlap in the genetic architecture of PD in Latinos compared to European-ancestry subjects, and to increase the diversity in PD genome-wide association (GWAS) data. METHODS: We genotyped and imputed 1,497 PD cases and controls recruited from nine clinical sites across South America. We performed a GWAS using logistic mixed models; variants with a p-value <1 × 10-5 were tested in a replication cohort of 1,234 self-reported Latino PD cases and 439,522 Latino controls from 23andMe, Inc. We also performed an admixture mapping analysis where local ancestry blocks were tested for association with PD status. RESULTS: One locus, SNCA, achieved genome-wide significance (p-value <5 × 10-8 ); rs356182 achieved genome-wide significance in both the discovery and the replication cohorts (discovery, G allele: 1.58 OR, 95% CI 1.35-1.86, p-value 2.48 × 10-8 ; 23andMe, G allele: 1.26 OR, 95% CI 1.16-1.37, p-value 4.55 × 10-8 ). In our admixture mapping analysis, a locus on chromosome 14, containing the gene STXBP6, achieved significance in a joint test of ancestries and in the Native American single-ancestry test (p-value <5 × 10-5 ). A second locus on chromosome 6, containing the gene RPS6KA2, achieved significance in the African single-ancestry test (p-value <5 × 10-5 ). INTERPRETATION: This study demonstrated the importance of the SNCA locus for the etiology of PD in Latinos. By leveraging the demographic history of our cohort via admixture mapping, we identified two potential PD risk loci that merit further study. ANN NEUROL 2021;90:353-365.

Transitional Care for Young People with Neurological Disorders: A Scoping Review with A Focus on Patients with Movement Disorders.

Childhood-onset movement disorders represent a heterogenous group of conditions. Given the complexity of these disorders, the transition of care from pediatric to adult medicine is an important consideration. We performed a scoping review of the literature on transitional care in chronic neurological disease, exploring key transitional issues and proposed transitional care models. Our aim was to describe the current knowledge and gaps about the transition process of young adults with chronic neurological disorders, paying special attention to childhood onset movement disorders. A total of 64 articles were included in the qualitative synthesis; 56 articles reported on transitional care issues, and 8 articles reported on transitional care models. Only 2 articles included patients with movement disorders. The following 4 main transitional issues were identified following synthesis of the available literature: (1) inadequate preparation for the transition process, (2) inappropriate and inconsistent transition practices, (3) inadequate adult services, and (4) heightened emotional response surrounding transition. Of the reported transitional care models, multidisciplinary ambulatory care was the most common approach. In studies evaluating patient-related outcomes, positive health, educational, and vocational outcomes were found. The available literature provides insights on issues that can arise during transition that should be addressed to improve patient and caregiver comfort and satisfaction with care. Further research is needed to evaluate how transitional care programs affect outcomes and their cost effectiveness. More studies are required to determine the needs and outcomes specific to patients with childhood onset movement disorders. © 2020 International Parkinson and Movement Disorder Society.

Genome-Wide Analysis of Copy Number Variation in Latin American Parkinson's Disease Patients.

BACKGROUND: Parkinson's disease is the second most common neurodegenerative disorder and affects people from all ethnic backgrounds, yet little is known about the genetics of Parkinson's disease in non-European populations. In addition, the overall identification of copy number variants at a genome-wide level has been understudied in Parkinson's patients. The objective of this study was to understand the genome-wide burden of copy number variants in Latinos and its association with Parkinson's disease. METHODS: We used genome-wide genotyping data from 747 Parkinson's disease patients and 632 controls from the Latin American Research Consortium on the Genetics of Parkinson's disease. RESULTS: Genome-wide copy number burden analysis showed that patients were significantly enriched for copy number variants overlapping known Parkinson's disease genes compared with controls (odds ratio, 3.97; 95%CI, 1.69-10.5; P = 0.018). PRKN showed the strongest copy number burden, with 20 copy number variant carriers. These patients presented an earlier age of disease onset compared with patients with other copy number variants (median age at onset, 31 vs 57 years, respectively; P = 7.46 × 10-7 ). CONCLUSIONS: We found that although overall genome-wide copy number variant burden was not significantly different, Parkinson's disease patients were significantly enriched with copy number variants affecting known Parkinson's disease genes. We also identified that of 250 patients with early-onset disease, 5.6% carried a copy number variant on PRKN in our cohort. Our study is the first to analyze genome-wide copy number variant association in Latino Parkinson's disease patients and provides insights about this complex disease in this understudied population. © 2020 International Parkinson and Movement Disorder Society.

Transitional Care for Young People with Movement Disorders: Consensus-Based Recommendations from the MDS Task Force on Pediatrics.

Background: The International Parkinson and Movement Disorders Society (MDS) set up a working group on pediatric movement disorders (MDS Task Force on Pediatrics) to generate recommendations to guide the transition process from pediatrics to adult health care systems in patients with childhood-onset movement disorders. Methods: To develop recommendations for transitional care for childhood onset movement disorders, we used a formal consensus development process, using a multi-round, web-based Delphi survey. The Delphi survey was based on the results of the scoping review of the literature and the results of a survey of MDS members on transition practices. Through iterative discussions, we generated the recommendations included in the survey. The MDS Task Force on Pediatrics were the voting members for the Delphi survey. The task force members comprise 23 child and adult neurologists with expertise in the field of movement disorders and from all regions of the world. Results: Fifteen recommendations divided across four different areas were made pertaining to: (1) team composition and structure, (2) planning and readiness, (3) goals of care, and (4) administration and research. All recommendations achieved consensus with a median score of 7 or greater. Conclusion: Recommendations on providing transitional care for patients with childhood onset movement disorders are provided. Nevertheless several challenges remain in the implementation of these recommendations, related to health infrastructure and the distribution of health resources, and the availability of knowledgeable and interested practitioners. Research on the influence of transitional care programs on outcomes in childhood onset movement disorders is much needed.

X-Chromosome Association Study in Latin American Cohorts Identifies New Loci in Parkinson Disease.

Sex differences in Parkinson Disease (PD) risk are well-known. However, it is still unclear the role of sex chromosomes in the development and progression of PD. We performed the first X-chromosome Wide Association Study (XWAS) for PD risk in Latin American individuals. We used data from three admixed cohorts: (i) Latin American Research consortium on the GEnetics of Parkinson's Disease (n=1,504) as discover cohort and (ii) Latino cohort from International Parkinson Disease Genomics Consortium (n = 155) and (iii) Bambui Aging cohort (n= 1,442) as replication cohorts. After developing a X-chromosome framework specifically designed for admixed populations, we identified eight linkage disequilibrium regions associated with PD. We fully replicated one of these regions (top variant rs525496; discovery OR [95%CI]: 0.60 [0.478 - 0.77], p = 3.13 × 10 -5 ; replication OR: 0.60 [0.37-0.98], p = 0.04). rs525496 is an expression quantitative trait loci for several genes expressed in brain tissues, including RAB9B, H2BFM, TSMB15B and GLRA4 . We also replicated a previous XWAS finding (rs28602900), showing that this variant is associated with PD in non-European populations. Our results reinforce the importance of including X-chromosome and diverse populations in genetic studies.

Polygenic risk prediction and SNCA haplotype analysis in a Latino Parkinson's disease cohort.

BACKGROUND: Large-scale Parkinson's disease (PD) genome-wide association studies (GWAS) have, until recently, only been conducted on subjects with European-ancestry. Consequently, polygenic risk scores (PRS) constructed using PD GWAS data are likely to be less predictive when applied to non-European cohorts. METHODS: Using GWAS data from the largest study to date, we constructed a PD PRS for a Latino PD cohort (1497 subjects from LARGE-PD) and tested it for association with PD status and age at onset. We validated the PRS performance by testing it in an independent Latino cohort (448 subjects) and by repeating the analysis in LARGE-PD with the addition of 440 external Peruvian controls. We also tested SNCA haplotypes for association with PD risk in LARGE-PD and a European-ancestry PD cohort. RESULTS: The GWAS-significant PD PRS had an area under the receiver-operator curve (AUC) of 0.668 (95% CI: 0.640-0.695) in LARGE-PD. The inclusion of external Peruvian controls mitigated this result, dropping the AUC 0.632 (95% CI: 0.607-0.657). At the SNCA locus, haplotypes differ by ancestry. Ancestry-specific SNCA haplotypes were associated with PD status in both LARGE-PD and the European-ancestry cohort (p-value < 0.05). These haplotypes both include the rs356182 G-allele, but only share 14% of their variants overall. CONCLUSION: The PD PRS has potential for PD risk prediction in Latinos, but variability caused by admixture patterns and bias in a European-ancestry PD PRS data limits its utility. The inclusion of diverse subjects can help elucidate PD risk loci and improve risk prediction in non-European cohorts.

The distribution and risk effect of GBA variants in a large cohort of PD patients from Colombia and Peru.

BACKGROUND: Mutations in the glucocerebrosidase (GBA) gene are an important risk factor for Parkinson's disease (PD). However, most GBA genetic studies in PD have been performed in patients of European origin and very few data are available in other populations. METHODS: We sequenced the entire GBA coding region in 602 PD patients and 319 controls from Colombia and Peru enrolled as part of the Latin American Research Consortium on the Genetics of Parkinson's disease (LARGE-PD). RESULTS: We observed a significantly higher proportion of GBA mutation carriers in patients compared to healthy controls (5.5% vs 1.6%; OR = 4.3, p = 0.004). Interestingly, the frequency of mutations in Colombian patients (9.9%) was more than two-fold greater than in Peruvian patients (4.2%) and other European-derived populations reported in the literature (4-5%). This was primarily due to the presence of a population-specific mutation (p.K198E) found only in the Colombian cohort. We also observed that the age at onset was significantly earlier in GBA carriers when compared to non-carriers (47.1 ±â€¯14.2 y vs. 55.9 ±â€¯14.2 y; p = 0.0004). CONCLUSION: These findings suggest that GBA mutations are strongly associated with PD risk and earlier age at onset in Peru and Colombia. The high frequency of GBA carriers among Colombian PD patients (∼10%) makes this population especially well-suited for novel therapeutic approaches that target GBA-related PD.

Erratum: Variable frequency of LRRK2 variants in the Latin American research consortium on the genetics of Parkinson's disease (LARGE-PD), a case of ancestry.

[This corrects the article DOI: 10.1038/s41531-017-0020-6.].

Variable frequency of LRRK2 variants in the Latin American research consortium on the genetics of Parkinson's disease (LARGE-PD), a case of ancestry.

Mutations in Leucine-Rich Repeat Kinase 2 (LRRK2), primarily located in codons G2019 and R1441, represent the most common genetic cause of Parkinson's disease in European-derived populations. However, little is known about the frequency of these mutations in Latin American populations. In addition, a prior study suggested that a LRRK2 polymorphism (p.Q1111H) specific to Latino and Amerindian populations might be a risk factor for Parkinson's disease, but this finding requires replication. We screened 1734 Parkinson's disease patients and 1097 controls enrolled in the Latin American Research Consortium on the Genetics of Parkinson's disease (LARGE-PD), which includes sites in Argentina, Brazil, Colombia, Ecuador, Peru, and Uruguay. Genotypes were determined by TaqMan assay (p.G2019S and p.Q1111H) or by sequencing of exon 31 (p.R1441C/G/H/S). Admixture proportion was determined using a panel of 29 ancestry informative markers. We identified a total of 29 Parkinson's disease patients (1.7%) who carried p.G2019S and the frequency ranged from 0.2% in Peru to 4.2% in Uruguay. Only two Parkinson's disease patients carried p.R1441G and one patient carried p.R1441C. There was no significant difference in the frequency of p.Q1111H in patients (3.8%) compared to controls (3.1%; OR 1.02, p = 0.873). The frequency of LRRK2-p.G2019S varied greatly between different Latin American countries and was directly correlated with the amount of European ancestry observed. p.R1441G is rare in Latin America despite the large genetic contribution made by settlers from Spain, where the mutation is relatively common.

Reply #1 to: Glycemic Choreoballism.

In Response To: Lee D, Ahn TB. Glycemic choreoballism. Tremor Other Hyperkinet Mov. 2016; 6. doi: 10.7916/D8QJ7HNF Original Article: Cosentino C, Torres L, Nuñez Y, et al. Hemichorea/hemiballism associated with hyperglycemia: report of twenty cases. Tremor Other Hyperkinet Mov. 2016; 6. doi: 10.7916/D8DN454P.

Hemichorea/Hemiballism Associated with Hyperglycemia: Report of 20 Cases.

BACKGROUND: Hemichorea/hemiballism associated with nonketotic hyperglycemia is a well-recognized syndrome, but few case series have been reported in the literature. CASE REPORT: We describe 20 patients with hemichorea/hemiballism associated with hyperglycemia (9 males and 11 females) with mean age of 67.8 years. Ten patients had a previous diagnosis of type 2 diabetes mellitus, and one had type 1 diabetes mellitus. Six of them had documentation of poor diabetic control over at least the last 3 months. Nine patients had new-onset hyperglycemia with a diagnosis of diabetes mellitus made after discharge. Seventeen patients had unilateral chorea/ballism, while three had bilateral chorea/ballism. Eighteen cases had striatal hyperdensities on computed tomography (CT) and/or hyperintense signals on magnetic resonance imaging (MRI). The putamen was affected in all cases, and the caudate nucleus was involved in nine. DISCUSSION: Hemichorea/hemiballism associated with nonketotic hyperglycemia can be the presenting sign of diabetes mellitus in almost half of cases or can occur after a few months of poor glycemic control in patients with diagnosed diabetes. This case series is one of the largest to date and adds valuable information about clinical and neuroimaging features that are comparable with published data but also emphasize the role of adequate diabetes mellitus control.

Bilateral Hypertrophic Olivary Degeneration and Holmes Tremor without Palatal Tremor: An Unusual Association.

BACKGROUND: Lesions in the Guillain-Mollaret triangle or dentate-rubro-olivary pathway may lead to hypertrophic olivary degeneration (HOD), a secondary trans-synaptic degeneration of the inferior olivary nucleus. HOD is usually associated with palatal tremor and rarely with Holmes tremor. Bilateral HOD is a very unusual condition and very few cases are reported. CASE REPORT: We report here two cases of bilateral HOD after two different vascular lesions located at the decussation of superior cerebellar peduncles, thus impairing both central tegmental tracts and interrupting bilaterally the dentate-rubral-olivary pathway. Interestingly, both developed bilateral Holmes tremor but not palatal tremor. DISCUSSION: Lesions in some of the components in the Guillain-Mollaret triangle may develop Holmes tremor with HOD and without palatal tremor. Magnetic resonance imaging is an invaluable tool in these cases. Better understanding of the pathways in this loop is needed.

The First Report of CADASIL in Peru: Olfactory Dysfunction on Initial Presentation.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL) is a rare, heritable, small vessel vascular disease caused by mutations in the Notch3 gene that is characterized by migraines, subcortical vascular events, cognitive decline, and mood disturbances. However, many CADASIL cases present with unusual symptoms such as status epilepticus, a movement disorder, or sensory dysfunction. This study describes the clinical, genetic, and radiologic characteristics of a Peruvian family with CADASIL in which multiple family members presented with severe olfactory deficits. Seven members of the family have symptoms suggestive of CADASIL, with genetic testing revealing R133C mutations in the two patients who underwent genetic testing. Cognitive testing and olfactory identification testing (Smell Identification Test) were performed in three CADASIL patients revealing total anosmia in two tested patients and severe hyposmia in the other. Olfactory dysfunction has been associated with various neurologic and psychiatric conditions though few studies have linked it with neurovascular disorders such as CADASIL. This first reported case of CADASIL in Peru emphasizes that symptomatic olfactory dysfunction may be an unusual presentation of CADASIL and that olfactory dysfunction is important to evaluate in CADASIL patients.

A Peruvian family with a novel PARK2 mutation: Clinical and pathological characteristics.

BACKGROUND: Mutations in PARK2 result in autosomal recessive young onset Parkinson's disease (YOPD). Although there have been a number of reports on the clinical characteristics of PARK2-related PD, there is limited information available on the associated neuropathologic changes. DESIGN: We describe the clinical and pathological characteristics of a Peruvian family with YOPD. The proband and one unaffected sibling were screened for PARK2 dosage and point mutations. One affected sibling had detailed neuropathologic examination. SETTING: Instituto Nacional de Ciencias Neurologicas (INCN) in Lima, Peru. RESULTS: The proband and two of her four siblings developed YOPD and both parents were unaffected. The clinical course has been characterized by akinetic-rigid parkinsonism predominantly affecting the lower limbs and dyskinesias. Analysis of PARK2 showed that the proband is compound heterozygous for a novel acceptor splice site mutation in intron 5 (IVS5-1G>A) and an exon 7 deletion. Neuropathologic assessment of an affected sibling revealed severe neuronal loss in the substantia nigra (SN) and loss of tyrosine hydroxylase immunopositive fibers in the striatum. No Lewy body pathology was observed using standard histology or immunohistochemistry for α-synuclein. CONCLUSIONS: Consistent with most neuropathologic reports of patients with PARK2 mutations, we did not observe Lewy body inclusions, despite marked SN degeneration and severe dopaminergic denervation of the striatum. These data describe a novel splice site mutation and further extend the clinicopathological characterization of PARK2-associated PD.

Cysticercosis lesions in basal ganglia are common but clinically silent.

Movement disorders due to basal ganglia involvement by neurocysticercosis are rarely seen. To evaluate the frequency of basal ganglia location of cysticercotic cysts and its clinical manifestations, baseline MRI scans of 120 consecutive patients with active neurocysticercosis were reviewed and the presence and number of active cysticercosis lesions (viable cysts or enhancing lesions) in the basal ganglia were recorded and correlated with demographic and clinical data. Basal ganglia involvement was found in 32 cases (26.7%). The frequency of lesions in basal ganglia was related to the total number of lesions, ranging from 5% of patients with a single cysticerci, to 60% in patients with more than five parasites. Putamen and caudate nuclei were the most frequent sites of lesions. No significant difference between both hemispheres was observed. Basal ganglia localization is common in neurocysticercosis but it is rarely associated with clinical manifestations.

Pan-American Consortium of Multiple System Atrophy (PANMSA). A Pan-American multicentre cohort study of multiple system atrophy.

BACKGROUND: Multiple system atrophy (MSA) is an adult-onset and rapidly progressive, neurodegenerative condition that presents with autonomic dysfunction, parkinsonism, cerebellar ataxia and corticospinal deficits. Clinical, demographic and epidemiological data from different regions have provided valuable information concerning the natural history of MSA. There are no published data of Multiple System Atrophy (MSA) in Latin American countries. OBJECTIVE: To describe clinical and epidemiological data of patients with "possible" MSA from seven referral movement disorders centers from Argentina, Chile, Mexico, Peru and United States. METHODS: We conducted a retrospective, observational, cross-sectional Pan-American multicentre cohort study of MSA. RESULTS: The sample was composed of 82 females and 77 men with the diagnosis of "possible" MSA with a mean age at onset of 65 ± 10 years. 67.29% of the individuals had a MSA-P variant with a mean age at onset of 61.47 ± 10.28 years, whereas the mean age at onset in the MSA-C patients was 57.44 ± 10.58 years. Interestingly, MSA-C-was more prevalent in Non-Caucasian (50-Mestizo and 2 Asian patients) than Caucasians (51.92% vs. 20.79%, p = 0.0001). Dysautonomic symptoms were present in 95.6% of the patients, parkinsonism in 85.5%, pyramidal signs in 25.8% and depression in 48.4% of the patients. CONCLUSIONS: Our epidemiological and clinical data appears to be similar to other Western international series, however, of note, the MSA-C phenotype was predominant in Non-Caucasians, more specifically the Mestizo population. This observation opens a new path to explore. Larger prospective epidemiologic studies in Latin America may provide valuable information concerning MSA in the region.