Exon Dosage Variations in Brazilian Patients with Parkinson’s Disease: Analysis ofSNCA,PARKIN,PINK1andDJ-1Genes

Parkinson’s disease is one of the most common neurodegenerative disorders associated with aging, reaching ∼ 2% of individuals over 65 years. Knowledge achieved in the last decade about the genetic basis of Parkinson’s disease clearly shows that genetic factors play an important role in the etiology of this disorder. Exon dosage variations account for a high proportion of Parkinson’s disease mutations, mainly forPARKINgene. In the present study, we screened genomic rearrangements inSNCA,PARKIN,PINK1andDJ-1genes in 102 Brazilian Parkinson’s disease patients with early onset (age of onset ≤ 50 years), using the multiplex ligation-dependent probe amplification method. Family history was reported by 24 patients, while 78 were sporadic cases. Screening of exon dosage revealedPARKINandPINK1copy number variations, but no dosage alteration was found inSNCAandDJ-1genes. Most of the carriers harbor heterozygous deletions or duplications in thePARKINgene and only one patient was found to have a deletion inPINK1exon 1. Data about dosage changes are scarce in the Brazilian population, which stresses the importance of including exon dosage analysis in Parkinson’s disease genetic studies.

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Analysis of Exon Dosage Using Multiplex Ligation-Dependent Probe Amplification in Chinese Patients with Early-Onset Parkinson’s Disease

European Neurology ◽

10.1159/000503421 ◽

2019 ◽

Vol 81 (5-6) ◽

pp. 246-253 ◽

Cited By ~ 3

Author(s):

Yu Lin ◽

Yi-Fang Zeng ◽

Nai-Qing Cai ◽

Xiao-Zhen Lin ◽

Ning Wang ◽

...

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Early Onset ◽

Clinical Investigation ◽

Quantitative Polymerase Chain Reaction ◽

Copy Number Variations ◽

Chinese Patients ◽

Incomplete Penetrance ◽

Exon 1 ◽

Dependent Probe

Introduction: Several studies have identified a number of genes associated with Parkinson’s disease (PD). Genomic rearrangements (exon dosage variations) in these genes have emerged as significant, causing mutations. However, exon dosage variations in several PD genes were rarely investigated in Chinese patients. Objective: This study was aimed at determining the prevalence of PD-causing genes’ exon rearrangements in Chinese sporadic early-onset PD (EOPD) patients. Methods: A total of 150 Chinese sporadic EOPD patients and 100 healthy controls were enrolled. Multiplex ligation-dependent probe amplification (MLPA) was used to detect exon dosage in PD genes, including SNCA, PARKIN, UCHL1, PINK1, DJ1, LRRK2, and ATP13A2. Positive results were verified by real-time quantitative polymerase chain reaction. And exon sequencing was employed to screen for subtle mutations. Novel exon dosage variations were screened in families and controls. Results: PARKIN exon rearrangements were detected in 10 (6.7%) patients, including a novel heterozygous duplication of PARKIN exons 1–4. Clinical investigation showed that the percentage of individuals with PARKIN exon rearrangements was higher in the younger patients. Notably, the MLPA screening detected a heterozygous deletion of UCHL1 exon 1 in a patient. MLPA analysis in the family detected the deletion in an asymptomatic sister, indicating incomplete penetrance. Conclusion: Exon copy number variations (CNVs) in the PARKIN gene are relatively common among Chinese sporadic EOPD patients, whereas exon CNVs in other known PD genes can also be detected. Our findings demonstrate that it is important to perform exon dosage analysis for several known PD genes to obtain a better mechanistic insight into PD pathogenesis.

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Parkinson’s Disease in Central Asian and Transcaucasian Countries: A Review of Epidemiology, Genetics, Clinical Characteristics, and Access to Care

Parkinson s Disease ◽

10.1155/2019/2905739 ◽

2019 ◽

Vol 2019 ◽

pp. 1-7

Author(s):

Rauan Kaiyrzhanov ◽

Mie Rizig ◽

Akbota Aitkulova ◽

Nazira Zharkinbekova ◽

Chingiz Shashkin ◽

...

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Clinical Characteristics ◽

Large Scale ◽

Age Of Onset ◽

Genetic Studies ◽

Related Data ◽

Central Asian ◽

The Mean ◽

Made In

Our understanding of Parkinson’s disease (PD) has significantly accelerated over the last few years, but predominant advances have been made in developed, Western countries. Little is known about PD in the Central Asian (CA) and Transcaucasian (TC) countries. Here, we review the clinical characteristics, treatments used, epidemiology, and genetics of PD in CA and TC countries via a methodological search in MEDLINE, EMBASE, Scopus, Web of Science, and Google Scholar databases. For the acquisition of PD care-related data, the search was extended to the local web resources. Our findings showed that PD prevalence in the region is averaging 62 per 100,000 population. The mean age of onset is 56.4 ± 2.8 in females and 63.3 ± 3.5 in males. Large-scale national studies on PD prevalence from the region are currently lacking. A limited number of genetic studies with small cohorts and inconclusive results were identified. The G2019S LRRK2 mutation, the commonest mutation in PD worldwide, was found in 5.7% of patients with idiopathic PD and 17.6% of familial cases in 153 Uzbek patients. Our review highlighted systematic deficiencies in PD health care in the region including lacks of neurologists specializing in PD, delays in PD diagnosis, absence of specialized PD nurses and PD rehab services, limited access to PD medications and surgery, and the unavailability of PD infusion therapies. Overall, this article demonstrated the paucity of data on this common neurological disorder in CA and TC countries and identified a number of healthcare areas that require an urgent consideration. We conclude that well-designed large-scale epidemiological, genetic, and clinical studies are desperately needed in this region. Healthcare professionals, local and national institutions, and stakeholders must come together to address deficiencies in PD healthcare systems in CA and TC countries.

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A Specific Diplotype H1j/H2 of the MAPT Gene Could Be Responsible for Parkinson’s Disease with Dementia

Case Reports in Genetics ◽

10.1155/2020/8813344 ◽

2020 ◽

Vol 2020 ◽

pp. 1-5

Author(s):

Imane Smaili ◽

Imane Hajjaj ◽

Rachid Razine ◽

Houyam Tibar ◽

Ayyoub Salmi ◽

...

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Rare Variants ◽

Neurodegenerative Disorder ◽

Age Of Onset ◽

Copy Number Variations ◽

Chromosome 17 ◽

G2019s Mutation ◽

Mapt Gene ◽

Genetic And Environmental Factors

Parkinson’s disease (PD) is the second most common neurodegenerative disorder after Alzheimer disease. Five to ten percent of patients have monogenic form of the disease, while most of sporadic PD cases are caused by the combination of genetic and environmental factors. Microtubule-associated protein tau (MAPT) has been appointed as one of the most important risk factors for several neurodegenerative diseases including PD. MAPT is characterized by an inversion in chromosome 17 resulting in two distinct haplotypes H1 and H2. Studies described a significant association of MAPT H1j subhaplotype with PD risk, while H2 haplotype was associated with Parkinsonism, particularly to its bradykinetic component. We report here an isolated case displaying an akinetic-rigid form of PD, with age of onset of 41 years and a good response to levodopa, who developed dementia gradually during the seven years of disease progression. The patient does not carry the LRRK2 G2019S mutation, copy number variations, nor pathogenic and rare variants in known genes associated with PD. MAPT subhaplotype genotyping revealed that the patient has the H1j/H2 diplotype, his mother H1j/H1j, his two healthy brothers H1j/H1v and his deceased father was by deduction H1v/H2. The H1j/H2 diplotype was shown in a total of 3 PD patients among 80, who also did not have known PD-causing mutation and in 1 out of 92 healthy individual controls. The three patients with this diplotype all have a similar clinical phenotype. Our results suggest that haplotypes H1j and H2 are strong risk factor alleles, and their combination could be responsible for early onset of PD with dementia.

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Gene Therapy for Parkinson’s Disease Associated with GBA1 Mutations

Journal of Parkinson s Disease ◽

10.3233/jpd-212739 ◽

2021 ◽

pp. 1-6

Author(s):

Asa Abeliovich ◽

Franz Hefti ◽

Jeffrey Sevigny

Keyword(s):

Parkinson’S Disease ◽

Gene Therapy ◽

Parkinson's Disease ◽

Clinical Trials ◽

Disease Risk ◽

Age Of Onset ◽

Normal Range ◽

Genetic Studies ◽

Lysosomal Dysfunction ◽

The Brain

Human genetic studies as well as studies in animal models indicate that lysosomal dysfunction plays a key role in the pathogenesis of Parkinson’s disease. Among the lysosomal genes involved, GBA1, has the largest impact on Parkinson’s disease risk. Deficiency in the GBA1 encoded enzyme glucocerebrosidase (GCase) leads to the accumulation of the GCase glycolipid substrates glucosylceramide and glucosylsphingosine and ultimately results in toxicity and inflammation and negatively affect many aspects of Parkinson’s disease, including disease risk, the severity of presentation, age of onset, and likelihood of progression to dementia. These findings support the view that re-establishing normal range levels of GCase expression and enzyme activity may reduce the progression of Parkinson’s disease in patients carrying GBA1 mutations. Studies in mouse models indicate that PR001, a rAAV9 vector-based gene therapy designed to deliver a functional GBA1 gene to the brain, suggest that this therapeutic approach may slow or stop disease progression. PR001 is currently being evaluated in clinical trials with Parkinson’s disease patients carrying GBA1 mutations.

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Hunting for Familial Parkinson’s Disease Mutations in the Post Genome Era

Genes ◽

10.3390/genes12030430 ◽

2021 ◽

Vol 12 (3) ◽

pp. 430

Author(s):

Steven R. Bentley ◽

Ilaria Guella ◽

Holly E. Sherman ◽

Hannah M. Neuendorf ◽

Alex M. Sykes ◽

...

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Family History ◽

Rare Variants ◽

Strong Family History ◽

Disease Mutations ◽

Whole Exome ◽

History Of ◽

Functional Consequences ◽

Multiplex Families

Parkinson’s disease (PD) is typically sporadic; however, multi-incident families provide a powerful platform to discover novel genetic forms of disease. Their identification supports deciphering molecular processes leading to disease and may inform of new therapeutic targets. The LRRK2 p.G2019S mutation causes PD in 42.5–68% of carriers by the age of 80 years. We hypothesise similarly intermediately penetrant mutations may present in multi-incident families with a generally strong family history of disease. We have analysed six multiplex families for missense variants using whole exome sequencing to find 32 rare heterozygous mutations shared amongst affected members. Included in these mutations was the KCNJ15 p.R28C variant, identified in five affected members of the same family, two elderly unaffected members of the same family, and two unrelated PD cases. Additionally, the SIPA1L1 p.R236Q variant was identified in three related affected members and an unrelated familial case. While the evidence presented here is not sufficient to assign causality to these rare variants, it does provide novel candidates for hypothesis testing in other modestly sized families with a strong family history. Future analysis will include characterisation of functional consequences and assessment of carriers in other familial cases.

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The TOMM40 ‘523’ polymorphism in disease risk and age of symptom onset in two independent cohorts of Parkinson’s disease

Scientific Reports ◽

10.1038/s41598-021-85510-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Megan C. Bakeberg ◽

Madison E. Hoes ◽

Anastazja M. Gorecki ◽

Frances Theunissen ◽

Abigail L. Pfaff ◽

...

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Symptom Onset ◽

Disease Risk ◽

Age Of Onset ◽

Sequencing Analysis ◽

Age Related ◽

Australian Cohort ◽

Progression Markers ◽

Age Related Cognitive Decline

AbstractAbnormal mitochondrial function is a key process in the pathogenesis of Parkinson’s disease (PD). The central pore-forming protein TOM40 of the mitochondria is encoded by the translocase of outer mitochondrial membrane 40 homologue gene (TOMM40). The highly variant ‘523’ poly-T repeat is associated with age-related cognitive decline and age of onset in Alzheimer’s disease, but whether it plays a role in modifying the risk or clinical course of PD it yet to be elucidated. The TOMM40 ‘523’ allele length was determined in 634 people with PD and 422 healthy controls from an Australian cohort and the Parkinson’s Progression Markers Initiative (PPMI) cohort, using polymerase chain reaction or whole genome sequencing analysis. Genotype and allele frequencies of TOMM40 ‘523’ and APOE ε did not differ significantly between the cohorts. Analyses revealed TOMM40 ‘523’ allele groups were not associated with disease risk, while considering APOE ε genotype. Regression analyses revealed the TOMM40 S/S genotype was associated with a significantly later age of symptom onset in the PPMI PD cohort, but not after correction for covariates, or in the Australian cohort. Whilst variation in the TOMM40 ‘523’ polymorphism was not associated with PD risk, the possibility that it may be a modifying factor for age of symptom onset warrants further investigation in other PD populations.

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