RAB32 Ser71Arg in autosomal dominant Parkinson's disease: linkage, association, and functional analyses

BACKGROUND

Parkinson's disease is a progressive neurodegenerative disorder with multifactorial causes, among which genetic risk factors play a part. The RAB GTPases are regulators and substrates of LRRK2, and variants in the LRRK2 gene are important risk factors for Parkinson's disease. We aimed to explore genetic variability in RAB GTPases within cases of familial Parkinson's disease.

METHODS

We did whole-exome sequencing in probands from families in Canada and Tunisia with Parkinson's disease without a genetic cause, who were recruited from the Centre for Applied Neurogenetics (Vancouver, BC, Canada), an international consortium that includes people with Parkinson's disease from 36 sites in 24 countries. 61 RAB GTPases were genetically screened, and candidate variants were genotyped in relatives of the probands to assess disease segregation by linkage analysis. Genotyping was also done to assess variant frequencies in individuals with idiopathic Parkinson's disease and controls, matched for age and sex, who were also from the Centre for Applied Neurogenetics but unrelated to the probands or each other. All participants were aged 18 years or older. The sequencing and genotyping findings were validated by case-control association analyses using bioinformatic data obtained from publicly available clinicogenomic databases (AMP-PD, GP2, and 100 000 Genomes Project) and a private German clinical diagnostic database (University of Tübingen). Clinical and pathological findings were summarised and haplotypes were determined. In-vitro studies were done to investigate protein interactions and enzyme activities.

FINDINGS

Between June 1, 2010, and May 31, 2017, 130 probands from Canada and Tunisia (47 [36%] female and 83 [64%] male; mean age 72·7 years [SD 11·7; range 38-96]; 109 White European ancestry, 18 north African, two east Asian, and one Hispanic] underwent whole-exome sequencing. 15 variants in RAB GTPase genes were identified, of which the RAB32 variant c.213C>G (Ser71Arg) cosegregated with autosomal dominant Parkinson's disease in three families (nine affected individuals; non-parametric linkage Z score=1·95; p=0·03). 2604 unrelated individuals with Parkinson's disease and 344 matched controls were additionally genotyped, and five more people originating from five countries (Canada, Italy, Poland, Turkey, and Tunisia) were identified with the RAB32 variant. From the database searches, in which 6043 individuals with Parkinson's disease and 62 549 controls were included, another eight individuals were identified with the RAB32 variant from four countries (Canada, Germany, UK, and USA). Overall, the association of RAB32 c.213C>G (Ser71Arg) with Parkinson's disease was significant (odds ratio [OR] 13·17, 95% CI 2·15-87·23; p=0·0055; I2=99·96%). In the people who had the variant, Parkinson's disease presented at age 54·6 years (SD 12·75, range 31-81, n=16), and two-thirds had a family history of parkinsonism. RAB32 Ser71Arg heterozygotes shared a common haplotype, although penetrance was incomplete. Findings in one individual at autopsy showed sparse neurofibrillary tangle pathology in the midbrain and thalamus, without Lewy body pathology. In functional studies, RAB32 Arg71 activated LRRK2 kinase to a level greater than RAB32 Ser71.

INTERPRETATION

RAB32 Ser71Arg is a novel genetic risk factor for Parkinson's disease, with reduced penetrance. The variant was found in individuals with Parkinson's disease from multiple ethnic groups, with the same haplotype. In-vitro assays show that RAB32 Arg71 activates LRRK2 kinase, which indicates that genetically distinct causes of familial parkinsonism share the same mechanism. The discovery of RAB32 Ser71Arg also suggests several genetically inherited causes of Parkinson's disease originated to control intracellular immunity. This shared aetiology should be considered in future translational research, while the global epidemiology of RAB32 Ser71Arg needs to be assessed to inform genetic counselling.

FUNDING

National Institutes of Health, the Canada Excellence Research Chairs program, Aligning Science Across Parkinson's, the Michael J Fox Foundation for Parkinson's Research, and the UK Medical Research Council.

A pathogenic variant in RAB32 causes autosomal dominant Parkinson's disease and activates LRRK2 kinase

Background

Parkinson's disease (PD) is a progressive neurodegenerative disorder. Mendelian forms have revealed multiple genes, with a notable emphasis on membrane trafficking; RAB GTPases play an important role in PD as a subset are both regulators and substrates of LRRK2 protein kinase. To explore the role of RAB GTPases in PD, we undertook a comprehensive examination of their genetic variability in familial PD.

Methods

Affected probands from 130 multi-incident PD families underwent whole-exome sequencing and genotyping, Potential pathogenic variants in 61 RAB GTPases were genotyped in relatives to assess disease segregation. These variants were also genotyped in a larger case-control series, totaling 3,078 individuals (2,734 with PD). The single most significant finding was subsequently validated within genetic data (6,043 with PD). Clinical and pathologic findings were summarized for gene-identified patients, and haplotypes were constructed. In parallel, wild-type and mutant RAB GTPase structural variation, protein interactions, and resultant enzyme activities were assessed.

Findings

We found RAB32 c.213C>G (Ser71Arg) to co-segregate with autosomal dominant parkinsonism in three multi-incident families. RAB32 Ser71Arg was also significantly associated with PD in case-control samples: genotyping and database searches identified thirteen more patients with the same variant that was absent in unaffected controls. Notably, RAB32 Ser71Arg heterozygotes share a common haplotype. At autopsy, one patient had sparse neurofibrillary tangle pathology in the midbrain and thalamus, without Lewy body pathology. In transfected cells the RAB32 Arg71 was twice as potent as Ser71 wild type to activate LRRK2 kinase.

Interpretation

Our study provides unequivocal evidence to implicate RAB32 Ser71Arg in PD. Functional analysis demonstrates LRRK2 kinase activation. We provide a mechanistic explanation to expand and unify the etiopathogenesis of monogenic PD.

Funding

National Institutes of Health, the Canada Excellence Research Chairs program, Aligning Science Across Parkinson's, the Michael J. Fox Foundation for Parkinson's Research, and the UK Medical Research Council.

P-326 Current real-world patterns of care for women diagnosed with uterine fibroids (UF) and heavy menstrual bleeding (HMB) in a predominantly African American (AA) population database

Study question

What are the clinical characteristics and patterns of care in African American women diagnosed with UF and HMB compared to White women?

Summary answer

The majority of the women were African American. Though similar in age, there were significant differences between the groups in multiple comorbidities and therapies.

What is known already

UF (leiomyomas) are common, benign uterine tumors affecting approximately 80% of African American and 70% of White women by age 50. In the United States, marked differences exist in disease presentation, severity, treatment, outcomes, and quality of life for African American women compared with White women. African American women typically develop uterine leiomyomas at a younger age, progress to clinically significant disease at an earlier age, have larger uteri at diagnosis and are more likely to be anemic. Limited data exist on the current clinical real-world characteristics and patterns of care for African American women with UF and HMB.

Study design, size, duration

This retrospective observational study identified women 18-55 years, with UF and HMB from IBM-Watson’s MarketScan® Multi-state Medicaid claims database between 2010-2019. The focus was on women with diagnoses of UF (index) and HMB, appearing on the same or different claims, continuously enrolled for > 12 months pre- and post-index (censored on claim for hysterectomy). A total of ≥ 24 months of observation was available for most patients.

Participants/materials, setting, methods

A total of 27,122 women met the inclusion criteria, 16,776 African Americans, 7,353 Whites, and 2,993 others or race unknown. The statistical analyses were carried out on the African American and White patients only. Descriptive analyses of baseline demographics, pre-index comorbidities and post-index treatment were performed. Chi-square tests analyses were applied to counts and t-tests analyses were applied to means. All tests used an alpha value of 0.05 for significance.

Main results and the role of chance

The majority of the analytical cohort of 24,129 women was African American (AA:69.5%; W:30.5 %). The mean (SD) follow-up time was 40.5 (24.7) months. The mean age was similar for both groups (AA:39.6 ± 7.11 years; W: 40.2 ± 7.23 years, p < 0.1). There were 48 pre-indexed comorbidities identified for analyses. The groups significantly differed on 14(29%) comorbidities. For 11 of the comorbidities, African American women were less likely to be diagnosed than White women (all Ps < 0.0001). Many of these diseases were related to bulk symptoms (e.g., pelvic pressure/pain), anxiety and depression. More African American women had diagnoses for diabetes (p = 0.0143), hypertension, and obesity (Ps < 0.0001). Though bulk symptoms were common in both groups, again fewer African American women were diagnosed than White (AA: 68.4%; W:77.0%, p < 0.0001).

Post-index, African American women were more likely treated with hormone-based therapy (42.4% vs. 38.5%, p < 0.0001). Contraceptives were the most frequent form of hormonal treatment prescribed (AA:39.9%; W:35.6%). African American were on contraceptives slightly longer than White women (AA: 377.3 (522.2 days); W: 323.1 (460.2 days) (p < 0.001). Fewer African American women had a hysterectomy (AA:32.0%; W:46.8%, p < 0.001).

Limitations, reasons for caution

This study was observational and descriptive in nature, which limits the ability to make conclusions regarding causality or identify women beyond the age and time constraints within the study. Additionally, claims data may be subject to reporting errors. This data is specific to Medicaid populations and may not be generalizable.

Wider implications of the findings

In this Medicaid population differences in clinical characteristics and UF treatment were evident between African American and White women. The breakdown of some comorbidities did not match national prevalence by race for these conditions (e.g., depression). Further analyses are needed to determine if these differences are clinically and socially meaningful.

Trial registration number

NA

Selective serotonin reuptake inhibitors (SSRIs) for stroke recovery

BACKGROUND

Selective serotonin reuptake inhibitors (SSRIs) might theoretically reduce post-stroke disability by direct effects on the brain. This Cochrane Review was first published in 2012 and last updated in 2019.

OBJECTIVES

To determine if SSRIs are more effective than placebo or usual care at improving outcomes in people less than 12 months post-stroke, and to determine whether treatment with SSRIs is associated with adverse effects.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (last searched 7 January 2021), Cochrane Controlled Trials Register (CENTRAL, Issue 7 of 12, 7 January 2021), MEDLINE (1946 to 7 January 2021), Embase (1974 to 7 January 2021), CINAHL (1982 to 7 January 2021), PsycINFO (1985 to 7 January 2021), and AMED (1985 to 7 January 2021). PsycBITE had previously been searched (16 July 2018). We searched clinical trials registers.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) recruiting stroke survivors within the first year. The intervention was any SSRI, at any dose, for any period, and for any indication. The comparator was usual care or placebo. Studies reporting at least one of our primary (disability score or independence) or secondary outcomes (impairments, depression, anxiety, quality of life, fatigue, cognition, healthcare cost, death, adverse events and leaving the study early) were included in the meta-analysis. The primary analysis included studies at low risk of bias.

DATA COLLECTION AND ANALYSIS

We extracted data on demographics, stroke type and, our pre-specified outcomes, and bias sources. Two review authors independently extracted data. We used mean difference (MD) or standardised mean differences (SMDs) for continuous variables, and risk ratios (RRs) for dichotomous variables, with 95% confidence intervals (CIs). We assessed bias risks and applied GRADE criteria.

MAIN RESULTS

We identified 76 eligible studies (13,029 participants); 75 provided data at end of treatment, and of these two provided data at follow-up. Thirty-eight required participants to have depression to enter. The duration, drug, and dose varied. Six studies were at low risk of bias across all domains; all six studies did not need participants to have depression to enter, and all used fluoxetine. Of these six studies, there was little to no difference in disability between groups SMD -0.0; 95% CI -0.05 to 0.05; 5 studies, 5436 participants, high-quality evidence) or in independence (RR 0.98; 95% CI 0.93 to 1.03; 5 studies, 5926 participants; high-quality evidence) at the end of treatment. In the studies at low risk of bias across all domains, SSRIs slightly reduced the average depression score (SMD 0.14 lower, 95% CI 0.19 lower to 0.08 lower; 4 studies; 5356 participants, high-quality evidence) and there was a slight reduction in the proportion with depression (RR 0.75, 95% CI 0.65 to 0.86; 3 studies, 5907 participants, high-quality evidence). Cognition was slightly better in the control group (MD -1.22, 95% CI -2.37 to -0.07; 4 studies, 5373 participants, moderate-quality evidence). Only one study (n = 30) reported neurological deficit score (SMD -0.39, 95% CI -1.12 to 0.33; low-quality evidence). SSRIs resulted in little to no difference in motor deficit (SMD 0.03, -0.02 to 0.08; 6 studies, 5518 participants, moderate-quality evidence). SSRIs slightly increased the proportion leaving the study early (RR 1.57, 95% CI 1.03 to 2.40; 6 studies, 6090 participants, high-quality evidence). SSRIs slightly increased the outcome of a seizure (RR 1.40, 95% CI 1.00 to 1.98; 6 studies, 6080 participants, moderate-quality evidence) and a bone fracture (RR 2.35, 95% CI 1.62 to 3.41; 6 studies, 6080 participants, high-quality evidence). One study at low risk of bias across all domains reported gastrointestinal side effects (RR 1.71, 95% CI 0.33, to 8.83; 1 study, 30 participants). There was no difference in the total number of deaths between SSRI and placebo (RR 1.01, 95% CI 0.82 to 1.24; 6 studies, 6090 participants, moderate quality evidence). SSRIs probably result in little to no difference in fatigue (MD -0.06; 95% CI -1.24 to 1.11; 4 studies, 5524 participants, moderate-quality of evidence), nor in quality of life (MD 0.00; 95% CI -0.02 to 0.02, 3 studies, 5482 participants, high-quality evidence). When all studies, irrespective of risk of bias, were included, SSRIs reduced disability scores but not the proportion independent. There was insufficient data to perform a meta-analysis of outcomes at end of follow-up. Several small ongoing studies are unlikely to alter conclusions.

AUTHORS' CONCLUSIONS

There is high-quality evidence that SSRIs do not make a difference to disability or independence after stroke compared to placebo or usual care, reduced the risk of future depression, increased bone fractures and probably increased seizure risk.

Selective serotonin reuptake inhibitors (SSRIs) for stroke recovery

BACKGROUND

Stroke is a major cause of adult disability. Selective serotonin reuptake inhibitors (SSRIs) have been used for many years to manage depression and other mood disorders after stroke. The 2012 Cochrane Review of SSRIs for stroke recovery demonstrated positive effects on recovery, even in people who were not depressed at randomisation. A large trial of fluoxetine for stroke recovery (fluoxetine versus placebo under supervision) has recently been published, and it is now appropriate to update the evidence.

OBJECTIVES

To determine if SSRIs are more effective than placebo or usual care at improving outcomes in people less than 12 months post-stroke, and to determine whether treatment with SSRIs is associated with adverse effects.

SEARCH METHODS

For this update, we searched the Cochrane Stroke Group Trials Register (last searched 16 July 2018), the Cochrane Controlled Trials Register (CENTRAL, Issue 7 of 12, July 2018), MEDLINE (1946 to July 2018), Embase (1974 to July 2018), CINAHL (1982 July 2018), PsycINFO (1985 to July 2018), AMED (1985 to July 2018), and PsycBITE March 2012 to July 2018). We also searched grey literature and clinical trials registers.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that recruited ischaemic or haemorrhagic stroke survivors at any time within the first year. The intervention was any SSRI, given at any dose, for any period, and for any indication. We excluded drugs with mixed pharmacological effects. The comparator was usual care or placebo. To be included, trials had to collect data on at least one of our primary (disability score or independence) or secondary outcomes (impairments, depression, anxiety, quality of life, fatigue, healthcare cost, death, adverse events and leaving the trial early).

DATA COLLECTION AND ANALYSIS

We extracted data on demographics, type of stroke, time since stroke, our primary and secondary outcomes, and sources of bias. Two review authors independently extracted data from each trial. We used standardised mean differences (SMDs) to estimate treatment effects for continuous variables, and risk ratios (RRs) for dichotomous effects, with their 95% confidence intervals (CIs). We assessed risks of bias and applied GRADE criteria.

MAIN RESULTS

We identified a total of 63 eligible trials recruiting 9168 participants, most of which provided data only at end of treatment and not at follow-up. There was a wide age range. About half the trials required participants to have depression to enter the trial. The duration, drug, and dose varied between trials. Only three of the included trials were at low risk of bias across the key 'Risk of bias' domains. A meta-analysis of these three trials found little or no effect of SSRI on either disability score: SMD -0.01 (95% CI -0.09 to 0.06; P = 0.75; 2 studies, 2829 participants; moderate-quality evidence) or independence: RR 1.00 (95% CI 0.91 to 1.09; P = 0.99; 3 studies, 3249 participants; moderate-quality evidence). We downgraded both these outcomes for imprecision. SSRIs reduced the average depression score (SMD 0.11 lower, 0.19 lower to 0.04 lower; 2 trials, 2861 participants; moderate-quality evidence), but there was a higher observed number of gastrointestinal side effects among participants treated with SSRIs compared to placebo (RR 2.19, 95% CI 1.00 to 4.76; P = 0.05; 2 studies, 148 participants; moderate-quality evidence), with no evidence of heterogeneity (I² = 0%). For seizures there was no evidence of a substantial difference. When we included all trials in a sensitivity analysis, irrespective of risk of bias, SSRIs appeared to reduce disability scores but not dependence. One large trial (FOCUS) dominated the results. We identified several ongoing trials, including two large trials that together will recruit more than 3000 participants.

AUTHORS' CONCLUSIONS

We found no reliable evidence that SSRIs should be used routinely to promote recovery after stroke. Meta-analysis of the trials at low risk of bias indicate that SSRIs do not improve recovery from stroke. We identified potential improvements in disability only in the analyses which included trials at high risk of bias. A further meta-analysis of large ongoing trials will be required to determine the generalisability of these findings.

Fluoxetine for stroke recovery: Meta-analysis of randomized controlled trials

OBJECTIVE

To determine whether fluoxetine, at any dose, given within the first year after stroke to patients who did not have to have mood disorders at randomization reduced disability, dependency, neurological deficits and fatigue; improved motor function, mood, and cognition at the end of treatment and follow-up, with the same number or fewer adverse effects.

METHODS

Searches (from 2012) in July 2018 included databases, trials registers, reference lists, and contact with experts. Co-primary outcomes were dependence and disability. Dichotomous data were synthesized using risk ratios (RR) and continuous data using standardized mean differences (SMD). Quality was appraised using Cochrane risk of bias methods. Sensitivity analyses explored influence of study quality.

RESULTS

The searches identified 3414 references of which 499 full texts were assessed for eligibility. Six new completed RCTs (n = 3710) were eligible, and were added to the seven trials identified in a 2012 Cochrane review (total: 13 trials, n = 4145). There was no difference in the proportion independent (3 trials, n = 3249, 36.6% fluoxetine vs. 36.7% control; RR 1.00, 95% confidence interval 0.91 to 1.09, p = 0.99, I² = 78%) nor in disability (7 trials n = 3404, SMD 0.05, -0.02 to 0.12 p = 0.15, I² = 81%) at end of treatment. Fluoxetine was associated with better neurological scores and less depression. Among the four (n = 3283) high-quality RCTs, the only difference between groups was lower depression scores with fluoxetine.

CONCLUSION

This class I evidence demonstrates that fluoxetine does not reduce disability and dependency after stroke but improves depression.

Simulation training for foundation doctors on the management of the acutely ill patient

BACKGROUND

A study evaluating subjective trainee responses to simulation training organized by the Malta Foundation Program in particular whether this changed their clinical practice.

METHOD

Feedback using a standardized questionnaire was obtained from 120 (M=55%) participants. A 0-10 Likert scale was used to evaluate responses.

RESULTS

Participants scored the simulation sessions as "useful" at 7.7 (95% confidence interval [CI] 7.4-8.0), rated "the overall experience" at 7.5 (95% CI 7.2-7.8), and thought it made a change in "daily practice" at 5.83 (95% CI 5.4-6.3). The score for the tutor "creating a satisfactory learning environment" and "quality of simulator equipment" was 7.8 (95% CI 7.6-8.1) and 7.7 (95% CI 7.4-8), respectively. Trainees rated "how close was the simulation to a real-life scenario" as 6.24 (95% CI 5.9-6.6). When asked whether the presence of colleagues hindered or helped, the majority were neutral 50 (41.7%), 36 (30%) said it hindered, while only 21 (28.3%) felt it helped. In contrast, 94 (78.33%) stated it was useful to observe colleagues while only 5 (4.2%) stated it was not. Likelihood for future participation was 7.4 (95% CI 7-7.8). Trainees recommended a median of 3 (interquartile range 2-5) simulations per year.

CONCLUSION

Trainees rated the sessions as useful and asked for more sessions possibly at an undergraduate level. Rating for equipment and tutors was positive; however, some felt that the effect on daily practice was limited. Most were comfortable observing others and uncomfortable being observed. The value of increasing sessions to 3-4 per year, timing them before clinical attachments and audiovisual prebriefing for candidates naïve to simulation needs to be evaluated in future studies.