Transforming Parkinson's Care in Africa (TraPCAf): protocol for a multimethodology National Institute for Health and Care Research Global Health Research Group project

BACKGROUND

Parkinson's disease (PD) is the second most common neurodegenerative disorder and, according to the Global Burden of Disease estimates in 2015, was the fastest growing neurological disorder globally with respect to associated prevalence, disability, and deaths. Information regarding the awareness, diagnosis, phenotypic characteristics, epidemiology, prevalence, risk factors, treatment, economic impact and lived experiences of people with PD from the African perspective is relatively sparse in contrast to the developed world, and much remains to be learned from, and about, the continent.

METHODS

Transforming Parkinson's Care in Africa (TraPCAf) is a multi-faceted, mixed-methods, multi-national research grant. The study design includes multiple sub-studies, combining observational (qualitative and quantitative) approaches for the epidemiological, clinical, risk factor and lived experience components, as appropriate, and interventional methods (clinical trial component). The aim of TraPCAf is to describe and gain a better understanding of the current situation of PD in Africa. The countries included in this National Institute for Health and Care Research (NIHR) Global Health Research Group (Egypt, Ethiopia, Ghana, Kenya, Nigeria, South Africa and Tanzania) represent diverse African geographies and genetic profiles, with differing resources, healthcare systems, health and social protection schemes, and policies. The research team is composed of experts in the field with vast experience in PD, jointly led by a UK-based and Africa-based investigator.

DISCUSSION

Despite the increasing prevalence of PD globally, robust data on the disease from Africa are lacking. Existing data point towards the poor awareness of PD and other neurological disorders on the continent and subsequent challenges with stigma, and limited access to affordable services and medication. This multi-site study will be the first of its kind in Africa. The data collected across the proposed sub-studies will provide novel and conclusive insights into the situation of PD. The selected country sites will allow for useful comparisons and make results relevant to other low- and middle-income countries. This grant is timely, as global recognition of PD and the public health challenge it poses builds. The work will contribute to broader initiatives, including the World Health Organization's Intersectoral global action plan on epilepsy and other neurological disorders.

TRIAL REGISTRATION

https://doi.org/10.1186/ISRCTN77014546 .

Case definitions for onchocerciasis-associated epilepsy and nodding syndrome: A focused review

Onchocerciasis-associated epilepsy (OAE) is an important but neglected public health problem in onchocerciasis-endemic areas with insufficient or inadequate onchocerciasis control. Hence, there is a need for an internationally accepted, easy-to-use epidemiological case definition of OAE to identify areas of high Onchocerca volvulus transmission and disease burden requiring treatment and prevention interventions. By including OAE as a manifestation of onchocerciasis, we will considerably improve the accuracy of the overall onchocerciasis disease burden, which is currently underestimated. Hopefully, this will lead to increased interest and funding for onchocerciasis research and control interventions, notably the implementation of more effective elimination measures and treatment and support for affected individuals and their families.

First familial Becker muscular dystrophy in Tanzania: Clinical and genetic features

In African neurological practice, muscle disorders are either underdiagnosed or underrepresented. This may in part be due to the large burden of other more common neurological disorders. In this report we describe the first Tanzanian patient with genetically confirmed Becker muscular dystrophy. His phenotype and genotype were compatible with elsewhere in the world. Remarkably, this patient reported his progressive weakness of the legs with difficulty in walking only after a fall. We demonstrate that muscular dystrophies occur in sub-Saharan Africa. Neurologists must however be aware that patients are likely to delay seeking medical care for muscle disorders.

FBXO7 mutations cause autosomal recessive, early-onset parkinsonian-pyramidal syndrome

BACKGROUND

The combination of early-onset, progressive parkinsonism with pyramidal tract signs has been known as pallido-pyramidal or parkinsonian-pyramidal syndrome since the first description by Davison in 1954. Very recently, a locus was mapped in a single family with an overlapping phenotype, and an FBXO7 gene mutation was nominated as the likely disease cause.

METHODS

We performed clinical and genetic studies in two families with early-onset, progressive parkinsonism and pyramidal tract signs.

RESULTS

An FBXO7 homozygous truncating mutation (Arg498Stop) was found in an Italian family, while compound heterozygous mutations (a splice-site IVS7 + 1G/T mutation and a missense Thr22Met mutation) were present in a Dutch family. We also found evidence of expression of novel normal splice-variants of FBXO7. The phenotype associated with FBXO7 mutations consisted of early-onset, progressive parkinsonism and pyramidal tract signs, thereby matching clinically the pallido-pyramidal syndrome of Davison. The parkinsonism exhibits varying degrees of levodopa responsiveness in different patients.

CONCLUSIONS

We conclusively show that recessive FBXO7 mutations cause progressive neurodegeneration with extrapyramidal and pyramidal system involvement, delineating a novel genetically defined entity that we propose to designate as PARK15. Understanding how FBXO7 mutations cause disease will shed further light on the molecular mechanisms of neurodegeneration, with potential implications also for more common forms of parkinsonism, such as Parkinson disease and multiple system atrophy.

PET neuroimaging and mutations in the DJ-1 gene

Mutations in the DJ-1 gene lead to autosomal recessive early-onset parkinsonism. We performed F-DOPA and FDG PET neuroimaging in two parkinsonism patients homozygous for DJ-1 mutations, three relatives heterozygous for a DJ-1 mutation and one non-carrier, all from the originally described kindred from The Netherlands. Their characteristics were compared to those of typical Parkinson's disease patients and healthy controls. Both parkinsonism patients had reduced F-DOPA uptake concordant with typical Parkinson's disease. In the, clinically unaffected, heterozygous relatives, F-DOPA metabolism was unremarkable, thus not suggesting a dosage effect of the DJ-1 gene.

A clinical-genetic study of Parkinson's disease in a genetically isolated community

The role of genetic factors in idiopathic, late-onset Parkinson's disease (PD) remains unclear, in spite of the recent advances in the genetics of early-onset forms of familial parkinsonism. There is increasing interest in using genetically isolated populations to unravel the genetics of complex diseases such as late-onset PD. We have studied genetic and clinical features of 109 patients with parkinsonism from an area comprising a genetically isolated population in the South-West of the Netherlands. Of the 109 patients with ascertained parkinsonism, 41 patients were diagnosed with PD and could be linked to a common founder 14 generations ago. The distribution of ages at onset of PD in the genetically isolated population was significantly bimodal, showing two peaks (one with a mean at age 67 years and another with a mean at 44 years, the former peak being significantly larger than that in a population-based study, the Rotterdam Study). In other clinical features, the only statistically significant difference between early-onset and late-onset PD was a decreased motor and cognitive function in patients with late-onset PD. Involvement of other PD genes including DJ-1, a gene implicated in a kindred with early-onset parkinsonism from the same genetic isolate, was excluded in other PD patients in the population. The finding of a common ancestor in 41 idiopathic-PD patients along with the exclusion of known PD genes and loci suggests the presence of at least one other, yet unknown, susceptibility gene involved in PD in this population.

Parkinson's disease: piecing together a genetic jigsaw

The role of genetics in the pathogenesis of Parkinson's disease has been subject to debate for decades. In recent years, the discovery of five genes and several more loci has provided important insight into its molecular aetiology. Some Parkinson's disease genes possibly cause Parkinson's disease by protein aggregation. The presence of Lewy bodies in carriers of mutations in one gene and their absence in carriers of another, however, still point towards a complex pathogenic network, with Parkinson's disease as a common clinical end point. The recent identification of the fourth and fifth Parkinson's disease genes suggests multiple pathways-an impaired oxidative stress defence for mutations in DJ-1, and a defect in another signalling pathway for mutations in NR4A2. Despite knowledge of genetics in familial Parkinson's disease, our knowledge of the common, late-onset form of Parkinson's disease remains limited. In non-familial Parkinson's disease, genes and environment probably interact to give rise to the disease. We review advances in the genetics of Parkinson's disease, focusing on the monogenic forms and their clinical and population-genetic consequences.

Autosomal recessive early onset parkinsonism is linked to three loci: PARK2, PARK6, and PARK7

Autosomal recessive, early onset parkinsonism (AREP) is genetically heterogeneous. Mutations in the parkin gene (PARK2 locus, chromosome 6q) account for up to 50% of AREP families. The parkin protein displays ubiquitin-ligase activity for different targets, which accumulate in the brain of patients with parkin defect and might cause neurodegeneration. Two new AREP loci (PARK6 and PARK7) have been recently mapped on chromosome 1p and confirmed in independent datasets, suggesting that both might be frequent. The three AREP forms display similar clinical phenotypes. Recruiting new families will help cloning the defective genes at PARK6 and PARK7 loci. This will contribute to unraveling the pathogenesis of AREP, and it is also expected to foster our understanding of molecular events underlying classic Parkinson's disease.

Park7, a novel locus for autosomal recessive early-onset parkinsonism, on chromosome 1p36

Although the role of genetic factors in the origin of Parkinson disease has long been disputed, several genes involved in autosomal dominant and recessive forms of the disease have been localized. Mutations associated with early-onset autosomal recessive parkinsonism have been identified in the Parkin gene, and recently a second gene, PARK6, involved in early-onset recessive parkinsonism was localized on chromosome 1p35-36. We identified a family segregating early-onset parkinsonism with multiple consanguinity loops in a genetically isolated population. Homozygosity mapping resulted in significant evidence for linkage on chromosome 1p36. Multipoint linkage analysis using MAPMAKER-HOMOZ generated a maximum LOD-score of 4.3, with nine markers spanning a disease haplotype of 16 cM. On the basis of several recombination events, the region defining the disease haplotype can be clearly separated, by > or =25 cM, from the more centromeric PARK6 locus on chromosome 1p35-36. Therefore, we conclude that we have identified on chromosome 1 a second locus, PARK7, involved in autosomal recessive, early-onset parkinsonism.