Joaquim J. Ferreira

Phenotype, genotype, and worldwide genetic penetrance of LRRK2-associated Parkinson's disease: a case-control study

Summary Background Mutations in LRRK2, the gene that encodes leucine-rich repeat kinase 2, are a cause of Parkinsons disease (PD). The International LRRK2 Consortium was established to answer three key clinical questions: can LRRK2-associated PD be distinguished from idiopathic PD; which mutations in LRRK2 are pathogenic; and what is the age-specific cumulative risk of PD for individuals who inherit or are at risk of inheriting a deleterious mutation in LRRK2? Methods Researchers from 21 centres across the world collaborated on this study. The frequency of the common LRRK2 Gly2019Ser mutation was estimated on the basis of data from 24 populations worldwide, and the penetrance of the mutation was defined in 1045 people with mutations in LRRK2 from 133 families. The LRRK2 phenotype was defined on the basis of 59 motor and non-motor symptoms in 356 patients with LRRK2-associated PD and compared with the symptoms of 543 patients with pathologically proven idiopathic PD. Findings Six mutations met the consortiums criteria for being proven pathogenic. The frequency of the common LRRK2 Gly2019Ser mutation was 1% of patients with sporadic PD and 4% of patients with hereditary PD; the frequency was highest in the middle east and higher in southern Europe than in northern Europe. The risk of PD for a person who inherits the LRRK2 Gly2019Ser mutation was 28% at age 59 years, 51% at 69 years, and 74% at 79 years. The motor symptoms (eg, disease severity, rate of progression, occurrence of falls, and dyskinesia) and non-motor symptoms (eg, cognition and olfaction) of LRRK2-associated PD were more benign than those of idiopathic PD. Interpretation Mutations in LRRK2 are a clinically relevant cause of PD that merit testing in patients with hereditary PD and in subgroups of patients with PD. However, this knowledge should be applied with caution in the diagnosis and counselling of patients. Funding UK Medical Research Council; UK Parkinsons Disease Society; UK Brain Research Trust; Internationaal Parkinson Fonds; Volkswagen Foundation; National Institutes of Health: National Institute of Neurological Disorders and Stroke and National Institute of Aging; Udall Parkinsons Disease Centre of Excellence; Pacific Alzheimer Research Foundation Centre; Italian Telethon Foundation; Fondazione Grigioni per il Morbo di Parkinson; Michael J Fox Foundation for Parkinsons Research; Safra Global Genetics Consortium; US Department of Veterans Affairs; French Agence Nationale de la Recherche.

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 Parkinsons 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 Parkinsons disease.

How common is the most common adult movement disorder? Update on the worldwide prevalence of essential tremor.

Essential tremor (ET) is among the more prevalent neurological disorders, yet prevalence estimates have varied enormously, making it difficult to establish prevalence with precision. We: (1) reviewed the worldwide prevalence of ET in population‐based epidemiological studies, (2) derived as precisely as possible an estimate of disease prevalence, and (3) examined trends and important differences across studies. We identified 28 population‐based prevalence studies (19 countries). In a meta‐analysis, pooled prevalence (all ages) = 0.9%, with statistically significant heterogeneity across studies (I2 = 99%, P < 0.001). In additional descriptive analyses, crude prevalence (all ages) = 0.4%. Prevalence increased markedly with age, and especially with advanced age. In the meta‐analysis, prevalence (age ≥ 65 years) = 4.6%, and in additional descriptive analyses, median crude prevalence (age ≥ 60–65) = 6.3%. In one study of those age ≥ 95 years, crude prevalence = 21.7%. Several studies reported ethnic differences in prevalence, although more studies are needed. Greater than one‐third of studies show a gender difference, with most demonstrating a higher prevalence among men. This possible gender preference is interesting given clinical, epidemiological, and pathological associations between ET and Parkinsons disease. Precise prevalence estimates such as those we provide are important because they form the numerical basis for planned public health initiatives, provide data on the background occurrence of disease for family studies, and offer clues about the existence of environmental or underlying biological factors of possible mechanistic importance.

A prevalence study of primary dystonia in eight European countries

There have been few epidemiological studies of dystonia. Most previous studies have provided estimates based on few cases. A European prevalence study was undertaken to provide more precise rates of dystonia by pooling data from eight European countries. Diagnosed cases were ascertained by adult neurologists with specialist movement disorders (and botulinum toxin) clinics. The crude annual period prevalence rate (1996–1997) for primary dystonia was 152 per million (95% confidence interval 142–162), with focal dystonia having the highest rate of 117 per million (108–126). Prevalence rates for cervical dystonia, blepharospasm and writers cramp were as follows: 57 (95% confidence interval 51–63), 36 (31–41), and 14 (11–17). The age-adjusted relative rates were significantly higher in women than in men for segmental and focus dystonias with the exception of writers cramp. Comparing rates between centres demonstrated significant variations for cervical dystonia, blepharospasm and writers cramp, probably due to methodological differences. Our results provide the first data on the prevalence of primary dystonia and its subtypes across several European countries. Due to under-ascertainment of cases, our rates should be seen as conservative and an under-estimate of the true prevalence of dystonia.Abstract There have been few epidemiological studies of dystonia. Most previous studies have provided estimates based on few cases. A European prevalence study was undertaken to provide more precise rates of dystonia by pooling data from eight European countries. Diagnosed cases were ascertained by adult neurologists with specialist movement disorders (and botulinum toxin) clinics. The crude annual period prevalence rate (1996–1997) for primary dystonia was 152 per million (95% confidence interval 142–162), with focal dystonia having the highest rate of 117 per million (108–126). Prevalence rates for cervical dystonia, blepharospasm and writers cramp were as follows: 57 (95% confidence interval 51–63), 36 (31–41), and 14 (11–17). The age-adjusted relative rates were significantly higher in women than in men for segmental and focus dystonias with the exception of writers cramp. Comparing rates between centres demonstrated significant variations for cervical dystonia, blepharospasm and writers cramp, probably due to methodological differences. Our results provide the first data on the prevalence of primary dystonia and its subtypes across several European countries. Due to under-ascertainment of cases, our rates should be seen as conservative and an under-estimate of the true prevalence of dystonia.

ATP13A2 missense mutations in juvenile parkinsonism and young onset Parkinson disease

Objective: To assess the prevalence, nature, and associated phenotypes of ATP13A2 gene mutations among patients with juvenile parkinsonism (onset <21 years) or young onset (between 21 and 40 years) Parkinson disease (YOPD). Methods: We studied 46 patients, mostly from Italy or Brazil, including 11 with juvenile parkinsonism and 35 with YOPD. Thirty-three cases were sporadic and 13 had positive family history compatible with autosomal recessive inheritance. Forty-two had only parkinsonian signs, while four (all juvenile-onset) had multisystemic involvement. The whole ATP13A2 coding region (29 exons) and exon-intron boundaries were sequenced from genomic DNA. Results: A novel homozygous missense mutation (Gly504Arg) was identified in one sporadic case from Brazil with juvenile parkinsonism. This patient had symptoms onset at age 12, levodopa-responsive severe akinetic-rigid parkinsonism, levodopa-induced motor fluctuations and dyskinesias, severe visual hallucinations, and supranuclear vertical gaze paresis, but no pyramidal deficit nor dementia. Brain CT scan showed moderate diffuse atrophy. Furthermore, two Italian cases with YOPD without atypical features carried a novel missense mutation (Thr12Met, Gly533Arg) in single heterozygous state. Conclusions: We confirm that ATP13A2 homozygous mutations are associated with human parkinsonism, and expand the associated genotypic and clinical spectrum, by describing a homozygous missense mutation in this gene in a patient with a phenotype milder than that initially associated with ATP13A2 mutations (Kufor-Rakeb syndrome). Our data also suggest that ATP13A2 single heterozygous mutations might be etiologically relevant for patients with YOPD and further studies of this gene in Parkinson disease are warranted.

Limitations of current Parkinson's disease therapy.

Levodopa and other dopaminergic medications drastically improve the motor symptoms and quality of life of patients with Parkinsons disease in the early stages of the disease. However, once the “honeymoon” period has waned, usually after a few years of dopaminergic therapy, patients become progressively more disabled despite an ever more complex combination of available antiparkinsonian treatments. Sooner or later, they suffer from “dopa‐resistant” motor symptoms (speech impairment, abnormal posture, gait and balance problems), “dopa‐resistant” nonmotor signs (autonomic dysfunction, mood and cognitive impairment, sleep problems, pain) and/or drug‐related side effects (especially psychosis, motor fluctuations, and dyskinesias). Therefore, the current antiparkinsonian therapy cannot be considered as ideal with regard to both efficacy and safety. Ann Neurol 2003;53 (suppl 3):S3–S15

Summary of the recommendations of the EFNS/MDS-ES review on therapeutic management of Parkinson's disease

To summarize the 2010 EFNS/MDS‐ES evidence‐based treatment recommendations for the management of Parkinsons disease (PD). This summary includes the treatment recommendations for early and late PD.

The G6055A (G2019S) mutation in LRRK2 is frequent in both early and late onset Parkinson’s disease and originates from a common ancestor

Background: Mutations in the gene Leucine-Rich Repeat Kinase 2 (LRRK2) were recently identified as the cause of PARK8 linked autosomal dominant Parkinson’s disease. Objective: To study recurrent LRRK2 mutations in a large sample of patients from Italy, including early (<50 years) and late onset familial and sporadic Parkinson’s disease. Results: Among 629 probands, 13 (2.1%) were heterozygous carriers of the G2019S mutation. The mutation frequency was higher among familial (5.1%, 9/177) than among sporadic probands (0.9%, 4/452) (p<0.002), and highest among probands with one affected parent (8.7%, 6/69) (p<0.001). There was no difference in the frequency of the G2019S mutation in probands with early v late onset disease. Among 600 probands, one heterozygous R1441C but no R1441G or Y1699C mutations were detected. None of the four mutations was found in Italian controls. Haplotype analysis in families from five countries suggested that the G2019S mutation originated from a single ancient founder. The G2019S mutation was associated with the classical Parkinson’s disease phenotype and a broad range of onset age (34 to 73 years). Conclusions: G2019S is the most common genetic determinant of Parkinson’s disease identified so far. It is especially frequent among cases with familial Parkinson’s disease of both early and late onset, but less common among sporadic cases. These findings have important implications for diagnosis and genetic counselling in Parkinson’s disease.

Scales to assess sleep impairment in Parkinson's disease: Critique and recommendations

There is a broad spectrum of sleep disturbances observed in Parkinsons disease (PD). A variety of scales have been applied to the evaluation of PD sleep and wakefulness, but only a small number have been assessed specifically for clinimetric properties in the PD population. The movement disorder society has commissioned this task force to examine these scales and to assess their use in PD. A systematic literature review was conducted to explore the use of sleep scales in PD and to determine which scales qualified for a detailed critique. The task force members, all of whom have extensive experience in assessing sleep in PD reviewed each of the scales using a structured proforma. Scales were categorized into recommended, suggested and listed according to predefined criteria. A total of 48 potential scales were identified from the search and reviewed. Twenty‐nine were excluded because they did not meet review criteria or were variations of scales already included, leaving 19 scales that were critiqued and rated by the task force based on the rating criteria. Only six were found to meet criteria for recommendation or suggestion by the task force: the PD sleep scale (PDSS) and the Pittsburgh sleep quality index (PSQI) are recommended for rating overall sleep problems to screen and to measure severity, the SCOPA‐sleep (SCOPA) is recommended for rating overall sleep problems both to screen and to measure severity, and for rating daytime sleepiness; the Epworth sleepiness scale (ESS) is recommended for rating daytime sleepiness to screen and to measure severity; the inappropriate sleep composite score (ISCS) is suggested for rating severe daytime sleepiness or sleep attacks to screen and to measure severity; and the Stanford sleepiness scale (SSS) is suggested for rating sleepiness and to measure severity at a specific moment. The task force does not recommend the development of new scales, but emphasizes the need for educational efforts to train physicians in sleep interview techniques and polysomnography.

Convergence of miRNA expression profiling, α-synuclein interacton and GWAS in Parkinson's disease.

miRNAs were recently implicated in the pathogenesis of numerous diseases, including neurological disorders such as Parkinsons disease (PD). miRNAs are abundant in the nervous system, essential for efficient brain function and play important roles in neuronal patterning and cell specification. To further investigate their involvement in the etiology of PD, we conducted miRNA expression profiling in peripheral blood mononuclear cells (PBMCs) of 19 patients and 13 controls using microarrays. We found 18 miRNAs differentially expressed, and pathway analysis of 662 predicted target genes of 11 of these miRNAs revealed an over-representation in pathways previously linked to PD as well as novel pathways. To narrow down the genes for further investigations, we undertook a parallel approach using chromatin immunoprecipitation-sequencing (ChIP-seq) analysis to uncover genome-wide interactions of α-synuclein, a molecule with a central role in both monogenic and idiopathic PD. Convergence of ChIP-seq and miRNomics data highlighted the glycosphingolipid biosynthesis and the ubiquitin proteasome system as key players in PD. We then tested the association of target genes belonging to these pathways with PD risk, and identified nine SNPs in USP37 consistently associated with PD susceptibility in three genome-wide association studies (GWAS) datasets (0.46≤OR≤0.63) and highly significant in the meta-dataset (3.36×10−4<p<1.94×10−3). A SNP in ST8SIA4 was also highly associated with PD (p = 6.15×10−3) in the meta-dataset. These findings suggest that several miRNAs may act as regulators of both known and novel biological processes leading to idiopathic PD.