Underrepresented Populations in Parkinson's Genetics Research: Current Landscape and Future Directions

BACKGROUND

Human genetics research lacks diversity; over 80% of genome-wide association studies have been conducted on individuals of European ancestry. In addition to limiting insights regarding disease mechanisms, disproportionate representation can create disparities preventing equitable implementation of personalized medicine.

OBJECTIVE

This systematic review provides an overview of research involving Parkinson's disease (PD) genetics in underrepresented populations (URP) and sets a baseline to measure the future impact of current efforts in those populations.

METHODS

We searched PubMed and EMBASE until October 2021 using search strings for "PD," "genetics," the main "URP," and and the countries in Latin America, Caribbean, Africa, Asia, and Oceania (excluding Australia and New Zealand). Inclusion criteria were original studies, written in English, reporting genetic results on PD from non-European populations. Two levels of independent reviewers identified and extracted information.

RESULTS

We observed imbalances in PD genetic studies among URPs. Asian participants from Greater China were described in the majority of the articles published (57%), but other populations were less well studied; for example, Blacks were represented in just 4.0% of the publications. Also, although idiopathic PD was more studied than monogenic forms of the disease, most studies analyzed a limited number of genetic variants. We identified just nine studies using a genome-wide approach published up to 2021, including URPs.

CONCLUSION

This review provides insight into the significant lack of population diversity in PD research highlighting the immediate need for better representation. The Global Parkinson's Genetics Program (GP2) and similar initiatives aim to impact research in URPs, and the early metrics presented here can be used to measure progress in the field of PD genetics in the future. © 2022 International Parkinson and Movement Disorder Society.

Dysphoric Milk Ejection Reflex: The Psychoneurobiology of the Breastfeeding Experience

Breastfeeding, given its biochemical and physiological basis, is known for its many benefits for both the lactating mother and the infant. Among the many challenges new breastfeeding mothers experience is the feeling of aversion in response to their newborn's suckling which has been termed dysphoric milk-ejection reflex (D-MER). Characterized by intense feelings of dysphoria which may eventually interfere with the mother's ability to breastfeed regularly, evidence suggests both the neurobiological and psychological basis of D-MER in an attempt to explain its complexity. Biologically, breastfeeding is expressed by the intracerebral release of oxytocin, an increased expression of oxytocin receptors in specific brain regions, increased mesocorticolimbic reward region activation, the secretion of prolactin and possibly the inhibition of dopamine. Hence, different theories explain D-MER in terms of disrupted neurotransmitter and hormonal activity. Breastfeeding has also proven to influence mood and stress reactivity in nursing mothers with a potential link with postpartum depression. Psychological theories attempt to explain D-MER from a sociopsychosexual lense shedding light on the significance of mother-infant attachment, the sexualization of the female body and the motherhood experience as a developmental stage in a woman's lifespan. The aim of this review is to provide a literature update of D-MER incorporating both neurobiological and psychological theories calling for raising awareness about the complexity of breastfeeding and for the need for mother-centered interventions for the management of D-MER and other postpartum-specific conditions.

Gut brain axis: an insight into microbiota role in Parkinson's disease

Parkinson's disease (PD) is one of the most common progressive neurodegenerative diseases. It is characterized neuropathologically by the presence of alpha-synuclein containing Lewy Bodies in the substantia nigra of the brain with loss of dopaminergic neurons in the pars compacta of the substantia nigra. The presence of alpha-synuclein aggregates in the substantia nigra and the enteric nervous system (ENS) drew attention to the possibility of a correlation between the gut microbiota and Parkinson's disease. The gut-brain axis is a two-way communication system, which explains how through the vagus nerve, the gut microbiota can affect the central nervous system (CNS), including brain functions related to the ENS, as well as how CNS can alter various gut secretions and immune responses. As a result, this dysbiosis or alteration in gut microbiota can be an early sign of PD with reported changes in short chain fatty acids, bile acids, and lipids. This gave rise to the use of probiotics and faecal microbiota transplantation as alternative approaches to improve the symptoms of patients with PD. The aim of this review is to discuss investigations that have been done to explore the gastrointestinal involvement in Parkinson's disease, the effect of dysbiosis, and potential therapeutic strategies for PD.

Mercury and Alzheimer's disease: a look at the links and evidence

This review paper investigates a specific environmental-disease interaction between mercury exposure and Alzheimer's disease hallmarks. Alzheimer's disease is a neurodegenerative disorder affecting predominantly the memory of the affected individual. It prevails mostly in the elderly, rendering many factors as possible causative agents, which potentially contribute to the disease pathogenicity cumulatively. Alzheimer's disease affects nearly 50 million people worldwide and is considered one the most devastating diseases not only for the patient, but also for their families and caregivers. Mercury is a common environmental toxin, found in the atmosphere mostly due to human activity, such as coal burning for heating and cooking. Natural release of mercury into the atmosphere occurs by volcanic eruptions, in the form of vapor, or weathering rocks. The most toxic form of mercury to humans is methylmercury, to which humans are exposed to by ingestion of fish. Methylmercury was found to exert its toxic effects on different parts of the human body, with predominance on the brain. There is no safe concentration for mercury in the atmosphere, even trace amounts can elicit harm to humans in the long term. Mercury's effect on Alzheimer's disease hallmarks formation, extracellular senile plaques and intracellular neurofibrillary tangles, has been widely studied. This review demonstrates the involvement of mercury, in its different forms, in the pathway of amyloid beta deposition and tau tangles formation. It aims to understand the link between mercury exposure and Alzheimer's disease so that, in the future, prevention strategies can be applied to halt the progression of this disease.

Association of insomnia with mania in Lebanese patients with bipolar disorder

OBJECTIVE

To assess: (1) the association between insomnia experienced at admission, sociodemographic and other patients' characteristics and mania; and (2) the variation of insomnia and mania before and after treatment in bipolar patients with manic episodes (type I).

METHODS

Sixty-two patients were interviewed shortly after their admission to the hospital (after 3 to 5 days). The current symptoms experienced by the patients were assessed upon admission and again at discharge from the hospital.

RESULTS

A poorer quality of sleep (higher PSQI scores) (Beta=0.590) was significantly associated with higher mania, whereas the intake of SSRIs (Beta=-5.952) and TCAs (Beta=-8.181) was significantly associated with lower mania. Furthermore, highly significant reductions were reported in the PSQI scores (4.96 vs. 2.75, P<0.001), ISI scores (8.30 vs. 3.45, P<0.001) and YMRS scores (8.60 vs. 3.06, P<0.001) between admission to and discharge from the hospital.

CONCLUSION

Insomnia in patients with bipolar disorder type I is associated with mania, with a significant reduction of sleep problems seen during a period of approximately 20 days of hospitalization. Further longitudinal studies are needed to confirm the validity of our results and identify the causes. In the meantime, this research recommends a strategy to improve sleeplessness experienced during inter-episode phases may be helpful in preventing manic episodes in BD.

Transcriptomic profiling of trophoblast fusion using BeWo and JEG-3 cell lines

In human placenta, alteration in trophoblast differentiation has a major impact on placental maintenance and integrity. However, little is known about the mechanisms that control cytotrophoblast fusion. The BeWo cell line is used to study placental function, since it forms syncytium and secretes hormones after treatment with cAMP or forskolin. In contrast, the JEG-3 cell line fails to undergo substantial fusion. Therefore, BeWo and JEG-3 cells were used to identify a set of genes responsible for trophoblast fusion. Cells were treated with forskolin for 48 h to induce fusion. RNA was extracted, hybridised to Affymetrix HuGene ST1.0 arrays and analysed using system biology. Trophoblast differentiation was evaluated by real-time PCR and immunocytochemistry analysis. Moreover, some of the identified genes were validated by real-time PCR and their functional capacity was demonstrated by western blot using phospho-specific antibodies and CRISPR/cas9 knockdown experiments. Our results identified a list of 32 altered genes in fused BeWo cells compared to JEG-3 cells after forskolin treatment. Among these genes, four were validated by RT-PCR, including salt-inducible kinase 1 (SIK1) gene which is specifically upregulated in BeWo cells upon fusion and activated after 2 min with forskolin. Moreover, silencing of SIK1 completely abolished the fusion. Finally, SIK1 was shown to be at the center of many biological and functional processes, suggesting that it might play a role in trophoblast differentiation. In conclusion, this study identified new target genes implicated in trophoblast fusion. More studies are required to investigate the role of these genes in some placental pathology.

Identification and characterization of HIV positive Ethiopian elite controllers in both Africa and Israel

OBJECTIVES

HIV elite controllers (ECs) are a unique subgroup of HIV-positive patients who are long-term virologically suppressed in the absence of antiretroviral treatment (ART). The prevalence of this subgroup is estimated to be < 1%. Various cohorts of ECs have been described in developed countries, most of which have been demographically heterogeneous. The aim of this study was to identify ECs in two large African cohorts and to estimate their prevalence in a relatively genetically homogenous population.

METHODS

We screened two cohorts of HIV-positive Ethiopian patients. The first cohort resided in Mekelle, Ethiopia. The second was comprised of HIV-positive Ethiopian immigrants in Israel. In the Mekelle cohort, ART-naïve subjects with stable CD4 counts were prospectively screened using two measurements of viral load 6 months apart. Subjects were defined as ECs when both measurements were undetectable. In the Israeli cohort, subjects with consistently undetectable viral loads (mean of 17 viral load measurements/patient) and stable CD4 count > 500 cells/μL were defined as ECs.

RESULTS

In the Mekelle cohort, 16 of 9515 patients (0.16%) fitted the definition of EC, whereas seven of 1160 (0.6%) in the Israeli cohort were identified as ECs (P = 0.011).

CONCLUSIONS

This is the first large-scale screening for HIV-positive ECs to be performed in entirely African cohorts. The overall prevalence of ECs is within the range of that previously described in developing countries. The significant difference in prevalence between the two cohorts of similar genetic background is probably a consequence of selection bias but warrants further investigation into possible environmental factors which may underlie the EC state.

[Veterinary medicine of the GDR in strained relations between technical instructions and political guidelines]

The development of Veterinary Medicine in the Soviet Occupation Zone in Germany and the former German Democratic Republic (GDR) is sketched in highlights. After the collectivization of agriculture (1960) a centralistically controlled national veterinary system was established. It was suited to the requirements of the industrially organized animal production. The successive classification of socialistic veterinary administration was associated with the following matters: the extension of veterinary subject matters, a vertical division of work with the aid of newly created technical veterinary professions, and a penetration of the profession with political guidelines. As the professional level of the veterinary system in the GDR was relatively high the reflection in retrospective needs to be evaluated in a differentiated way considering the textual and social conditions. In spite of centralism and indoctrination the veterinary system remained professionally autonomous with islands of political independence, which sustained the identity of this profession. The latter formed the base for self renewal of the East German veterinary system at the end of the socialistic area 1989/1990.

Comparison of systematic versus selective screening for methicillin-resistant Staphylococcus aureus carriage in a high-risk dermatology ward

OBJECTIVE

To compare two strategies for screening methicillin-resistant Staphylococcus aureus (MRSA) carriers in a high-risk dermatology ward: systematic screening of all admitted patients versus selective screening of patients at risk.

DESIGN

The two strategies were applied prospectively during two consecutive periods. In period A (8.5 months), only patients transferred from other wards, or with a history of prior hospitalization, or presenting chronic wounds or disease with denuded skin were considered at high risk of MRSA carriage and sampled. In period B (7.5 months), all admitted patients were systematically screened. End-points were the number of patients having a MRSA-positive screening sample on admission during period B and having none of the risk factors used in period A, the rate of imported MRSA cases, and the rate of acquired cases.

SETTING

A 1,032-bed university hospital with a 19-bed inpatient dermatology ward, a referral center for toxic epidermal necrolysis and severe extensive dermatoses.

PATIENTS

The study included 729 dermatology inpatients (370 in period A and 359 in period B).

RESULTS

During period A, screening samples were obtained on admission for 30% of patients (77% of the patients at risk) and identified 25 MRSA carriers. During period B, 90.5% of admitted patients were screened, and 26 MRSA carriers were detected on admission; all of these patients belonged to at least one predefined category at risk for carriage. Overall rates of imported and acquired cases were similar between the two periods (6.8% vs 7.5%, and 2.9% vs 2.4%, respectively).

CONCLUSIONS

A screening strategy targeted to patients at risk of harboring MRSA has similar sensitivity and is more cost-effective than a strategy of systematic screening to identify MRSA carriers on admission.

[Pilotropic T-cell lymphoma without mucinosis: 5 new cases]

BACKGROUND

Pilotropic cutaneous T-cell lymphomas without mucinosis are rare, with 27 cases previously reported. Diagnosis and classification may be difficult. The clinical course and histopathological and immunohistochemical findings in 5 patients are described.

PATIENTS AND METHODS

Patients were selected from the register of the French Study Group for cutaneous lymphomas. The criteria for inclusion were clinical pilofollicular manifestations and histological features of pilotropic T-cell lymphoma without mucinosis.

RESULTS

Five patients were selected. The most frequent clinical manifestations were follicular keratosis, alopecia and follicular papules. Typical lesions of mycosis fongoides were present for several years in 3 patients, and lymphomatoid papulosis preexisted in one patient. Histopathological analysis showed an infiltrate composed of CD3+ and CD4+ atypical lymphocytes involving the follicular epithelium with alteration of the hair follicle walls. Epidermotropism was associated with pilotropism and situated near the follicular lesions or farther apart. Alcian blue stains results were negative in all specimens. PCR studies showed the presence of a T-cell clone in the skin lesions in all cases.

COMMENTS

Diagnosis of pilotropic cutaneous T cell lymphomas without mucinosis may be difficult in case of discrete epidermotropism, minimal infiltrate or involvement of the follicular epithelium. Pilotropism could define a particular variant of T-cell lymphomas.

[Foreign bodies of the respiratory tract in children. A retrospective study of 100 cases]

Foreign body inhalation is a universal problem, most common cause of death from domestic accident in children aged five years and less. Over 15 years, one hundred children aged less than six years were evaluated in Hotel Dieu de France; findings are comparable to previous data, with one avoidable death; boys are chiefly concerned (64%); mean age is 22.5 months; circumstances are often hazy (65%); vegetables are prominently responsible (90%) especially peanuts and pistachios (48%); foreign bodies are seldom radiopaque (1%); autumnal predominance is noted. Inhalation is not reported in 25% of cases; immediate risk is subglottic impaction; the child survives if the foreign body is expelled one way or another. The most frequent site is the bronchial system (87%) with a slight right predominance (49%); symptoms include: dyspnea, persistent cough, and, in case of bronchial obstruction: wheezing and asymmetry of breath sounds; 15% of children are free of symptoms. Delay before hospital care is long (21.5 days), mostly because diagnosis is misread particularly in case of bronchial foreign body; pulmonary distension is a frequent finding (45%). In case of asphyxia, first aid resuscitation is performed immediately: in fact it is rarely useful, sometimes harmful. Extraction is mandatory with the stiff bronchoscope; otherwise, bronchopulmonary infection and destruction is the usual outcome ... (25%). Management is revisited, and prevention is recalled.