Neuromuscular disease genetics in under-represented populations: increasing data diversity

Neuromuscular diseases (NMDs) affect ∼15 million people globally. In high income settings DNA-based diagnosis has transformed care pathways and led to gene-specific therapies. However, most affected families are in low-to-middle income countries (LMICs) with limited access to DNA-based diagnosis. Most (86%) published genetic data is derived from European ancestry. This marked genetic data inequality hampers understanding of genetic diversity and hinders accurate genetic diagnosis in all income settings. We developed a cloud-based transcontinental partnership to build diverse, deeply-phenotyped and genetically characterized cohorts to improve genetic architecture knowledge, and potentially advance diagnosis and clinical management. We connected 18 centres in Brazil, India, South Africa, Turkey, Zambia, Netherlands and the UK. We co-developed a cloud-based data solution and trained 17 international neurology fellows in clinical genomic data interpretation. Single gene and whole exome data were analysed via a bespoke bioinformatics pipeline and reviewed alongside clinical and phenotypic data in global webinars to inform genetic outcome decisions. We recruited 6001 participants in the first 43 months. Initial genetic analyses 'solved' or 'possibly solved' ∼56% probands overall. In-depth genetic data review of the four commonest clinical categories (limb girdle muscular dystrophy, inherited peripheral neuropathies, congenital myopathy/muscular dystrophies and Duchenne/Becker muscular dystrophy) delivered a ∼59% 'solved' and ∼13% 'possibly solved' outcome. Almost 29% of disease causing variants were novel, increasing diverse pathogenic variant knowledge. Unsolved participants represent a new discovery cohort. The dataset provides a large resource from under-represented populations for genetic and translational research. In conclusion, we established a remote transcontinental partnership to assess genetic architecture of NMDs across diverse populations. It supported DNA-based diagnosis, potentially enabling genetic counselling, care pathways and eligibility for gene-specific trials. Similar virtual partnerships could be adopted by other areas of global genomic neurological practice to reduce genetic data inequality and benefit patients globally.

The mutational profile in a South African cohort with inherited neuropathies and spastic paraplegia

Introduction

Limited diagnostics are available for inherited neuromuscular diseases (NMD) in South Africa and (excluding muscle disease) are mainly aimed at the most frequent genes underlying genetic neuropathy (GN) and spastic ataxias in Europeans. In this study, we used next-generation sequencing to screen 61 probands with GN, hereditary spastic paraplegia (HSP), and spastic ataxias for a genetic diagnosis.

Methods

After identifying four GN probands with PMP22 duplication and one spastic ataxia proband with SCA1, the remaining probands underwent whole exome (n = 26) or genome sequencing (n = 30). The curation of coding/splice region variants using gene panels was guided by allele frequencies from internal African-ancestry control genomes (n = 537) and the Clinical Genome Resource's Sequence Variant Interpretation guidelines.

Results

Of 32 GN probands, 50% had African-genetic ancestry, and 44% were solved: PMP22 (n = 4); MFN2 (n = 3); one each of MORC2, ATP1A1, ADPRHL2, GJB1, GAN, MPZ, and ATM. Of 29 HSP probands (six with predominant ataxia), 66% had African-genetic ancestry, and 48% were solved: SPG11 (n = 3); KIF1A (n = 2); and one each of SPAST, ATL1, SPG7, PCYT2, PSEN1, ATXN1, ALDH18A1, CYP7B1, and RFT1. Structural variants in SPAST, SPG11, SPG7, MFN2, MPZ, KIF5A, and GJB1 were excluded by computational prediction and manual visualisation.

Discussion

In this preliminary cohort screening panel of disease genes using WES/WGS data, we solved ~50% of cases, which is similar to diagnostic yields reported for global cohorts. However, the mutational profile among South Africans with GN and HSP differs substantially from that in the Global North.

Analysis of Structural Variants Previously Associated With ALS in Europeans Highlights Genomic Architectural Differences in Africans

Background and Objectives

Amyotrophic lateral sclerosis (ALS) is a degenerative condition of the brain and spinal cord in which protein-coding variants in known ALS disease genes explain a minority of sporadic cases. There is a growing interest in the role of noncoding structural variants (SVs) as ALS risk variants or genetic modifiers of ALS phenotype. In small European samples, specific short SV alleles in noncoding regulatory regions of SCAF4, SQSTM1, and STMN2 have been reported to be associated with ALS, and several groups have investigated the possible role of SMN1/SMN2 gene copy numbers in ALS susceptibility and clinical severity.

Methods

Using short-read whole genome sequencing (WGS) data, we investigated putative ALS-susceptibility SCAF4 (3'UTR poly-T repeat), SQSTM1 (intron 5 AAAC insertion), and STMN2 (intron 3 CA repeat) alleles in African ancestry patients with ALS and described the architecture of the SMN1/SMN2 gene region. South African cases with ALS (n = 114) were compared with ancestry-matched controls (n = 150), 1000 Genomes Project samples (n = 2,336), and H3Africa Genotyping Chip Project samples (n = 347).

Results

There was no association with previously reported SCAF4 poly-T repeat, SQSTM1 AAAC insertion, and long STMN2 CA alleles with ALS risk in South Africans (p > 0.2). Similarly, SMN1 and SMN2 gene copy numbers did not differ between South Africans with ALS and matched population controls (p > 0.9). Notably, 20% of the African samples in this study had no SMN2 gene copies, which is a higher frequency than that reported in Europeans (approximately 7%).

Discussion

We did not replicate the reported association of SCAF4, SQSTM1, and STMN2 short SVs with ALS in a small South African sample. In addition, we found no link between SMN1 and SMN2 copy numbers and susceptibility to ALS in this South African sample, which is similar to the conclusion of a recent meta-analysis of European studies. However, the SMN gene region findings in Africans replicate previous results from East and West Africa and highlight the importance of including diverse population groups in disease gene discovery efforts. The clinically relevant differences in the SMN gene architecture between African and non-African populations may affect the effectiveness of targeted SMN2 gene therapy for related diseases such as spinal muscular atrophy.

Factors associated with the severity of COVID-19 outcomes in people with neuromuscular diseases: Data from the International Neuromuscular COVID-19 Registry

BACKGROUND AND PURPOSE

Clinical outcome information on patients with neuromuscular diseases (NMDs) who have been infected with SARS-CoV-2 is limited. The aim of this study was to determine factors associated with the severity of COVID-19 outcomes in people with NMDs.

METHODS

Cases of NMD, of any age, and confirmed/presumptive COVID-19, submitted to the International Neuromuscular COVID-19 Registry up to 31 December 2021, were included. A mutually exclusive ordinal COVID-19 severity scale was defined as follows: (1) no hospitalization; (2) hospitalization without oxygenation; (3) hospitalization with ventilation/oxygenation; and (4) death. Multivariable ordinal logistic regression analyses were used to estimate odds ratios (ORs) for severe outcome, adjusting for age, sex, race/ethnicity, NMD, comorbidities, baseline functional status (modified Rankin scale [mRS]), use of immunosuppressive/immunomodulatory medication, and pandemic calendar period.

RESULTS

Of 315 patients from 13 countries (mean age 50.3 [±17.7] years, 154 [48.9%] female), 175 (55.5%) were not hospitalized, 27 (8.6%) were hospitalized without supplemental oxygen, 91 (28.9%) were hospitalized with ventilation/supplemental oxygen, and 22 (7%) died. Higher odds of severe COVID-19 outcomes were observed for: age ≥50 years (50-64 years: OR 2.4, 95% confidence interval [CI] 1.33-4.31; >64 years: OR 4.16, 95% CI 2.12-8.15; both vs. <50 years); non-White race/ethnicity (OR 1.81, 95% CI 1.07-3.06; vs. White); mRS moderately severe/severe disability (OR 3.02, 95% CI 1.6-5.69; vs. no/slight/moderate disability); history of respiratory dysfunction (OR 3.16, 95% CI 1.79-5.58); obesity (OR 2.24, 95% CI 1.18-4.25); ≥3 comorbidities (OR 3.2, 95% CI 1.76-5.83; vs. ≤2; if comorbidity count used instead of specific comorbidities); glucocorticoid treatment (OR 2.33, 95% CI 1.14-4.78); and Guillain-Barré syndrome (OR 3.1, 95% CI 1.35-7.13; vs. mitochondrial disease).

CONCLUSIONS

Among people with NMDs, there is a differential risk of COVID-19 outcomes according to demographic and clinical characteristics. These findings could be used to develop tailored management strategies and evidence-based recommendations for NMD patients.

A single low-dose rituximab infusion in severe chronic refractory myasthenia gravis in resource-limited settings

The benefits of multi-dose rituximab cycles in patients with refractory anti-muscle-specific kinase antibody myasthenia gravis (MuSK+MG) are well reported, although less consistently in anti-acetylcholine receptor antibody MG (AChR+MG). Responsivity data to single low-dose rituximab infusions for refractory autoimmune myasthenia, are limited. Here, observational outcomes using MG grading scores and prednisone doses, before and after at least six months of a single-dose infusion of rituximab, were audited in previously treatment-refractory MG patients in a resource-limited setting. Seventeen moderately-severe to severely symptomatic MG patients received single low-dose rituximab infusions (median 500-600 mg) after a median MG duration of 6 years; 13 individuals responded including 5/5 MuSK+MG, 7/10 AChR+MG and 1/2 double seronegative MG. Three (60%) MuSK+MG and three (30%) AChR+MG achieved persistent asymptomatic status. Although more MuSK+MG vs AChR+MG cases stopped prednisone (80% vs 20%, respectively), the prednisone doses in the AChR+MG group was significantly reduced ≥30% (p = 0.008) due to improved MG composite scores (p = 0.016) and with durable benefit (median 12 months). There were no differences between responders and non-responders in MG duration and age at infusion. These results suggest that a single low-dose rituximab infusion is worth trying in refractory MG, including AChR+MG patients, as some patients showed good and durable responses. These results are particularly relevant to resource-limited settings.

Post-Infectious Autoimmunity in the Central (CNS) and Peripheral (PNS) Nervous Systems: An African Perspective

The direct impact and sequelae of infections in children and adults result in significant morbidity and mortality especially when they involve the central (CNS) or peripheral nervous system (PNS). The historical understanding of the pathophysiology has been mostly focused on the direct impact of the various pathogens through neural tissue invasion. However, with the better understanding of neuroimmunology, there is a rapidly growing realization of the contribution of the innate and adaptive host immune responses in the pathogenesis of many CNS and PNS diseases. The balance between the protective and pathologic sequelae of immunity is fragile and can easily be tipped towards harm for the host. The matter of immune privilege and surveillance of the CNS/PNS compartments and the role of the blood-brain barrier (BBB) and blood nerve barrier (BNB) makes this even more complex. Our understanding of the pathogenesis of many post-infectious manifestations of various microbial agents remains elusive, especially in the diverse African setting. Our exploration and better understanding of the neuroimmunology of some of the infectious diseases that we encounter in the continent will go a long way into helping us to improve their management and therefore lessen the burden. Africa is diverse and uniquely poised because of the mix of the classic, well described, autoimmune disease entities and the specifically "tropical" conditions. This review explores the current understanding of some of the para- and post-infectious autoimmune manifestations of CNS and PNS diseases in the African context. We highlight the clinical presentations, diagnosis and treatment of these neurological disorders and underscore the knowledge gaps and perspectives for future research using disease models of conditions that we see in the continent, some of which are not uniquely African and, where relevant, include discussion of the proposed mechanisms underlying pathogen-induced autoimmunity. This review covers the following conditions as models and highlight those in which a relationship with COVID-19 infection has been reported: a) Acute Necrotizing Encephalopathy; b) Measles-associated encephalopathies; c) Human Immunodeficiency Virus (HIV) neuroimmune disorders, and particularly the difficulties associated with classical post-infectious autoimmune disorders such as the Guillain-Barré syndrome in the context of HIV and other infections. Finally, we describe NMDA-R encephalitis, which can be post-HSV encephalitis, summarise other antibody-mediated CNS diseases and describe myasthenia gravis as the classic antibody-mediated disease but with special features in Africa.

Mitochondrial bioenergetics in ocular fibroblasts of two myasthenia gravis cases

Myasthenia gravis (MG) is a rare, treatable, antibody-mediated disease characterized by fatigable muscle weakness of extraocular muscles (EOMs) and non-ocular skeletal muscles. The antibodies are directed against muscle-endplate proteins, most frequently the acetylcholine receptor (AChR) alpha-subunit. Although most MG patients respond to immunosuppressive treatment, some individuals, frequently with African-genetic ancestry, develop treatment-resistant ophthalmoplegia (OP-MG). Although the underlying pathogenetic mechanisms of OP-MG remain unknown, experimental rodent models of MG showed upregulation of genes involved in oxidative metabolism in muscles. EOMs are highly dependent on oxidative metabolism. We opportunistically sampled EOM-tendons of two rare OP-MG patients (and non-MG controls) undergoing re-alignment surgery, and established ocular fibroblast cultures. Metabolic assays were performed on these live cells to assess real-time differences in energy metabolism. To study the cellular bioenergetic profiles in the context of MG, we exposed the cultures to homologous 5% MG sera for 24 h, vs. growth media, from two independent MG patients (with circulating AChR-antibodies) and five controls without MG, and estimated the fold change in oxygen consumption rates in response to three compounds which inhibit different mitochondrial chain complexes. Quantitative PCR (qPCR) was performed in cells before and after MG sera exposure, to assess transcript levels of mitochondrial genes, PDK4, ANGPTL4 and UCP3, which were altered in experimental MG. In response to the mitochondrial stressors, basal oxidative metabolism parameters were similar between OP-MG and control fibroblasts (p = 0.81). However, after exposure to MG sera, bioenergetic parameters (oxygen consumption rate as an indicator of oxidative phosphorylation; extracellular acidification rate as an indicator of glycolysis), were induced to higher levels in OP-MG fibroblasts compared to controls (2.6-fold vs 1.5-fold; p = 0.031) without evidence of mitochondrial insufficiency in the OP-MG ocular fibroblasts. In support of the bioenergetic responses to the same MG sera, gene transcripts of PDK4 and ANGPLT4 in ocular fibroblasts also showed significant upregulation (p ≤ 0.041), but similarly in OP-MG and control cases. Taken together we showed similar basal and metabolic adaptive responses after exposure to mitochondrial inhibitors in ocular fibroblasts derived from OP-MG cases and controls, although the OP-MG cells showed greater activation in response to MG conditions. These pilot results in orbital-derived tissues provide support for myasthenic-induced changes in cellular metabolism and evidence that orbital fibroblasts may be useful for dynamic bioenergetic assessments.

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Orbital fibroblasts may be useful for dynamic bioenergetic assays.

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Orbital-fibroblast cultures showed shifts in oxidative metabolism induced by homologous myasthenic sera.

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Altered bioenergetic adaptation was induced by MG sera in orbital fibroblasts from ophthalmoplegic MG patients compared to controls.

A review of the genetic spectrum of hereditary spastic paraplegias, inherited neuropathies and spinal muscular atrophies in Africans

Background

Genetic investigations of inherited neuromuscular disorders in Africans, have been neglected. We aimed to summarise the published data and comment on the genetic evidence related to inherited neuropathies (Charcot-Marie-Tooth disease (CMT)), hereditary spastic paraplegias (HSP) and spinal muscular atrophy (SMA) in Africans.

Methods

PubMed was searched for relevant articles and manual checking of references and review publications were performed for African-ancestry participants with relevant phenotypes and identified genetic variants. For each case report we extracted phenotype information, inheritance pattern, variant segregation and variant frequency in population controls (including up to date frequencies from the gnomAD database).

Results

For HSP, 23 reports were found spanning the years 2000–2019 of which 19 related to North Africans, with high consanguinity, and six included sub-Saharan Africans. For CMT, 19 reports spanning years 2002–2021, of which 16 related to North Africans and 3 to sub-Saharan Africans. Most genetic variants had not been previously reported. There were 12 reports spanning years 1999–2020 related to SMN1-SMA caused by homozygous exon 7 ± 8 deletion. Interestingly, the population frequency of heterozygous SMN1-exon 7 deletion mutations appeared 2 × lower in Africans compared to Europeans, in addition to differences in the architecture of the SMN2 locus which may impact SMN1-SMA prognosis.

Conclusions

Overall, genetic data on inherited neuromuscular diseases in sub-Saharan Africa, are sparse. If African patients with rare neuromuscular diseases are to benefit from the expansion in genomics capabilities and therapeutic advancements, then it is critical to document the mutational spectrum of inherited neuromuscular disease in Africa.

Highlights

Review of genetic variants reported in hereditary spastic paraplegia in Africans

Review of genetic variants reported in genetic neuropathies in Africans

Review of genetic underpinnings of spinal muscular atrophies in Africans

Assessment of pathogenic evidence for candidate variants

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-022-02280-2.

The Epidemiology and Phenotypes of Ocular Manifestations in Childhood and Juvenile Myasthenia Gravis: A Review

Myasthenia gravis (MG) appears to have a similar incidence among adult populations worldwide. However, epidemiological and phenotypic differences have been noted among children and juveniles with MG. We reviewed the literature on childhood- and juvenile-onset MG among different populations, with the focus on ocular involvement, antibody profiles, the genetic susceptibility to juvenile MG phenotypes, the use of immune treatments, and the reported responses of extraocular muscles to therapies. Although epidemiological studies used different methodologies, reports from Asia, compared to Europe, showed more than two-fold higher proportions of prepubertal onset (before 12 years) vs. postpubertal-onset juveniles with MG. Compared to European children, ocular MG was 4-fold more frequent among Asian children, and 2–3-fold more frequent among children with African ancestry both in prepubertal and postpubertal ages at onset. These results suggest genetic influences. In Asia, HLA-B^*46 and DRB1^*09 appeared overrepresented in children with ocular MG. In Europe, children with MG had a significantly higher rate of transforming from ocular to generalized disease and with an overrepresentation of HLADRB1^*04. Although treatment regimens vary widely and the responses to immune therapies of the ocular muscles involved in MG were generally poorly described, there were indications that earlier use of steroid therapy may have better outcomes. Reports of treatment-resistant ophthalmoplegia may be more frequent in African and Asian juvenile MG cohorts compared to Europeans. Genetic and muscle gene expression studies point to dysregulated muscle atrophy signaling and mitochondrial metabolism pathways as pathogenetic mechanisms underpinning treatment-resistant ophthalmoplegia in susceptible individuals. In conclusion, phenotypic differences in juveniles with ocular manifestations of MG were evident in different populations suggesting pathogenetic influences. Treatment responses in MG-associated ocular disease should attract more careful descriptive reports. In MG, extraocular muscles may be vulnerable to critical periods of poor force generation and certain individuals may be particularly susceptible to developing treatment-resistant ophthalmoplegia. The development of prognostic biomarkers to identify these susceptible individuals is an unmet need.

Adaptation and norming of the Edinburgh Cognitive and behavioural amyotrophic lateral sclerosis screen (ECAS) for three language groups in South Africa

Objectives: To adapt and translate the Edinburgh Cognitive and behavioural amyotrophic lateral sclerosis screen (ECAS); to generate preliminary normative data for three language groups in South Africa (SA); to assess the convergent validity of the ECAS in SA samples. Methods: The ECAS was linguistically and culturally adapted for Afrikaans-, isiXhosa-, and English-speaking SA adults (n = 108, 100, and 53, respectively). Each language group was stratified by age and educational level. Cutoff scores for cognitive impairment were set at the group mean minus two standard deviations (SDs). A pilot sample of ALS patients and controls (n = 21 each) were administered the ECAS and an extensive neuropsychological evaluation (NPE) and the Montreal Cognitive Assessment (MoCA) to assess convergent validity. Results: Across the three language groups, the total ECAS cutoff scores ranged from 68 to 97. The ECAS score correlated significantly positively with educational level (p < 0.001) and negatively with age (p < 0.005). The restricted letter fluency task demonstrated a floor effect, particularly in Afrikaans-speakers. The mean total ECAS score (±SD) was similar in ALS patients (103.52 ± 11.90) and controls (100.67 ± 20.49; p = 0.58). Three (14.3%) ALS patients scored below the cutoff for cognitive impairment. Correlations between individual ECAS subtests and analogous NPE tests ranged from weak to moderate. The MoCA score was significantly positively correlated with the ECAS total score (r = 0.59; p = < 0.001). Conclusions: The adapted ECAS and associated normative data will aid cognitive screening of African ALS patients. Larger participant numbers are needed to assess the validity of the adapted instrument.

Revealing the Mutational Spectrum in Southern Africans With Amyotrophic Lateral Sclerosis

Background and Objectives

To perform the first screen of 44 amyotrophic lateral sclerosis (ALS) genes in a cohort of African genetic ancestry individuals with ALS using whole-genome sequencing (WGS) data.

Methods

One hundred three consecutive cases with probable/definite ALS (using the revised El Escorial criteria), and self-categorized as African genetic ancestry, underwent WGS using various Illumina platforms. As population controls, 238 samples from various African WGS data sets were included. Our analysis was restricted to 44 ALS genes, which were curated for rare sequence variants and classified according to the American College of Medical Genetics guidelines as likely benign, uncertain significance, likely pathogenic, or pathogenic variants.

Results

Thirteen percent of 103 ALS cases harbored pathogenic variants; 5 different SOD1 variants (N87S, G94D, I114T, L145S, and L145F) in 5 individuals (5%, 1 familial case), pathogenic C9orf72 repeat expansions in 7 individuals (7%, 1 familial case) and a likely pathogenic ANXA11 (G38R) variant in 1 individual. Thirty individuals (29%) harbored ≥1 variant of uncertain significance; 10 of these variants had limited pathogenic evidence, although this was insufficient to permit confident classification as pathogenic.

Discussion

Our findings show that known ALS genes can be expected to identify a genetic cause of disease in >11% of sporadic ALS cases of African genetic ancestry. Similar to European cohorts, the 2 most frequent genes harboring pathogenic variants in this population group are C9orf72 and SOD1.

Repeats expansions in ATXN2, NOP56, NIPA1 and ATXN1 are not associated with ALS in Africans

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized primarily by progressive loss of motor neurons. Although ALS occurs worldwide and the frequency and spectrum of identifiable genetic causes of disease varies across populations, very few studies have included African subjects. In addition to a hexanucleotide repeat expansion (RE) in C9orf72, the most common genetic cause of ALS in Europeans, REs in ATXN2, NIPA1 and ATXN1 have shown variable associations with ALS in Europeans. Intermediate range expansions in some of these genes (e.g. ATXN2) have been reported as potential risk factors, or phenotypic modifiers, of ALS. Pathogenic expansions in NOP56 cause spinocerebellar ataxia-36, which can present with prominent motor neuron degeneration. Here we compare REs in these genes in a cohort of Africans with ALS and population controls using whole genome sequencing data. Targeting genotyping of short tandem repeats at known loci within ATXN2, NIPA1, ATXN1 and NOP56 was performed using ExpansionHunter software in 105 Southern African (SA) patients with ALS. African population controls were from an in-house SA population control database (n = 25), the SA Human Genome Program (n = 24), the Simons Genome Diversity Project (n = 39) and the Illumina Polaris Diversity Cohort (IPDC) dataset (n = 50). We found intermediate RE alleles in ATXN2 (27-33 repeats) and ATXN1 (33-35 repeats), and NIPA1 long alleles (≥8 repeats) were rare in Africans, and not associated with ALS (p > 0.17). NOP56 showed no expanded alleles in either ALS or controls. We also compared the differences in allele distributions between the African and n = 50 European controls (from the IPDC). There was a statistical significant difference in the distribution of the REs in the ATXN1 between African and European controls (Chi-test p < 0.001), and NIPA1 showed proportionately more longer alleles (RE > 8) in Europeans vs. Africans (Fisher's p = 0.016). The distribution of RE alleles in ATXN2 and NOP56 were similar amongst African and European controls. In conclusion, repeat expansions in ATXN2, NIPA1 and ATXN1, which showed associations with ALS in Europeans, were not replicated in Southern Africans with ALS.

Tuberculosis in Myasthenia Gravis patients on immunosuppressive therapy in a high-risk area: Implications for preventative therapy

Data regarding the risk of tuberculosis (TB) in myasthenia gravis (MG) patients receiving immunosuppressive therapy is limited, and the benefit of TB preventative therapy in these patients is uncertain. We audited observational data collected at an MG clinic in South Africa over a ~ 10-year period, of cases who received immunosuppressive therapy. The total time that the cohort was at risk (patient-years) was used as the denominator to calculate TB incidence after immunosuppressive therapy initiation. Multivariate logistic regression analysis was performed to identify differences between patients who did, and those who did not, develop TB. Of 480 cases, only two received TB preventative therapy when starting immunotherapy. Seventeen of 282 (6%) patients tested, were HIV-infected. With a median follow-up of 3.6 years (interquartile range 1;7.5), 13 (3%) patients (all HIV-uninfected) developed TB (38% within 12 months of starting immunosuppressive therapy). The incidence rate of TB in the study population (≤401/100000 person-years) was not higher than that for the hospital's catchment area during the same period (>500/100000 population). The maximum dose of prescribed prednisone was higher in patients who developed TB compared to those who did not (median: 0.6 mg/kg/day vs 0.4; 0.002); Odds ratio for TB increased 1.26-fold for every 0.1 mg/kg/day increase in maximum dose (p = 0.001). In our TB endemic setting, receiving immunosuppressive therapy was not associated with excess TB in MG patients. Preventative therapy may be considered in those who are at greatest risk of developing TB and receiving high-dose prednisone.

Gene expression profiling of orbital muscles in treatment-resistant ophthalmoplegic myasthenia gravis

Background

Unbiased in silico approaches applied to genome-wide data prioritized putative functional gene variants associating with treatment-resistant ophthalmoplegic myasthenia gravis (OP-MG). Although altered expression of genes harbouring these variants, or associated pathways, were shown in patient-derived transdifferentiated-myocyte models, gene expression in orbital-derived muscle was required to test the validity of the predictions.

Methods

We sampled orbicularis oculi muscle (OOM) and one paralysed extraocular muscle (EOM) from six individuals with OP-MG during blepharoptosis and re-alignment surgeries, respectively. For controls, the OOMs were sampled from four individuals without myasthenia undergoing surgery for non-muscle causes of ptosis, and one non-paralysed EOM. Using a qPCR array, expression of 120 genes was compared between OP-MG and control OOMs, profiling putative “OP-MG” genes, genes in related biological pathways and genes reported to be dysregulated in MG cases or experimental MG models, and in EOMs of cases with strabismus. Normalization was performed with two stable reference genes. Differential gene expression was compared between OP-MG and control samples using the ΔΔCT method. Co-expression was analysed by pairwise correlation of gene transcripts to infer expression networks.

Results

Overall, transcript levels were similar in OOMs and EOMs (p = 0.72). In OOMs, significant downregulated expression of eight genes was observed in OP-MG cases compared with controls (> twofold; p ≤ 0.016), including TFAM, a mitochondrial transcription factor, and genes related to the following pathways: atrophy signalling; muscle regeneration and contraction; glycogen synthesis; and extracellular matrix remodelling. Several microRNAs, known to be highly expressed in EOMs, are predicted to regulate some of these genes. Co-expression analyses of gene-pairs suggested high interconnectedness of gene expression networks in OP-MG muscle, but not controls (r > 0.96, p < 0.01). Significant inverse directions of gene-pair correlations were noted in OP-MG versus controls OOM networks (r ≥ 0.92, p < 0.001) involving most OP-MG genes overlapping prominently with muscle atrophy/contractility and oxidative metabolism genes.

Conclusions

The gene expression in orbital muscles derived from OP-MG individuals compared with normal controls, support the pathogenic hypothesis previously generated from whole genome sequence analyses. Repression of gene transcripts in OP-MG orbital muscle implicate tissue-specific regulatory mechanisms, which may inform future biomarker discovery approaches.

Incidence of motor neuron disease/amyotrophic lateral sclerosis in South Africa: a 4-year prospective study

BACKGROUND AND PURPOSE

Little is known about the epidemiological features of amyotrophic lateral sclerosis (ALS) in sub-Saharan Africa, and data from the region are limited to clinical series or case reports. The aim of the study was to investigate the incidence rate and presentation of ALS in an ethnically diverse region of South Africa.

METHODS

We performed a 4-year prospective incidence study in the Western Cape Province of South Africa between 1 July 2014 and 30 June 2018, and used a two-source capture-recapture method for case ascertainment. Age- and sex-adjusted incidence rates (ASAIRs) were calculated using the 2010 US population as the reference.

RESULTS

A total of 203 incident cases were identified over the study period, resulting in a crude incidence rate (IR) of 1.09 [95% confidence interval (CI) 0.94-1.24] per 100 000 person-years in the at-risk population (aged >15 years). Capture-recapture analysis resulted in an estimated IR of 1.11 (95% CI 1.01-1.22) per 100 000 person-years. The ASAIR was 1.67 (95% CI 1.09-2.26) overall; 1.99 (95% CI 1.60-2.39) for men and 1.37 (95% CI 1.06-1.68) for women. When analysed separately, there was a substantial difference in ASAIRs between the different population groups, with the highest in the European ancestry group (2.62; 95% CI 2.49-2.75), the lowest in the African ancestry group (0.56, 95% CI 0.0-1.23), and an ASAIR in between these two in the mixed ancestry group (1.09, 95% CI 0.80-1.37).

CONCLUSION

The overall incidence of ALS in the Western Cape Province of South Africa appears to be lower than in North African and Western countries, but higher than in Asian countries. As suggested by previous epidemiological studies, ALS may be less frequent in people of African ancestry.

Management Issues in Myasthenia Gravis Patients Living With HIV: A Case Series and Literature Review

South Africa is home to more than seven million people living with human immunodeficiency virus (HIV) and a high prevalence of tuberculosis. Human immunodeficiency virus–infected individuals may develop myasthenia gravis (MG), which raises questions regarding their management. An MG database, with 24 years of observational data, was audited for HIV-infected persons. Case reports of MG in HIV-infected persons were reviewed. We identified 17 persons with MG and HIV infection. All had generalized MG with a mean age at onset of 37.8 years. Eleven had acetylcholine receptor antibody–positive MG; one had antibodies against muscle-specific kinase. Six developed MG prior to HIV infection (mean CD4⁺ 361 cells/mm³); four worsened <6 months of starting antiretrovirals. Eleven developed MG while HIV-infected (mean CD4⁺ 423 cells/mm³); five presented with mild MG; three in MG crisis requiring rescue therapies (intravenous immune globulin or plasma exchange and/or intravenous cyclophosphamide). Two were diagnosed with HIV infection and MG at the same time. Fifteen required maintenance steroid-sparing immune therapies, predominantly azathioprine, or methotrexate. Plasma HIV viral loads remained below detectable levels on antiretrovirals during immunosuppressant treatment. Over the average follow-up of 6 years, 10 achieved minimal manifestation status, and the remainder improved to mild symptoms. Three cases had tuberculosis before MG, but none developed tuberculosis reactivation on immunosuppressive therapy; one used isoniazid prophylaxis. Herpes zoster reactivation during treatment occurred in one. Conclusions include the following: MG in HIV-infected patients should be managed similarly to individuals without HIV infection; half develop moderate–severe MG; MG symptoms may worsen within 6 months of antiretroviral initiation; safety monitoring must include plasma HIV viral load estimation. Isoniazid prophylaxis may not be indicated in all cases.

Minimal manifestation status and prednisone withdrawal in the MGTX trial

OBJECTIVE

To examine whether sustained minimal manifestation status (MMS) with complete withdrawal of prednisone is better achieved in thymectomized patients with myasthenia gravis (MG).

METHODS

This study is a post hoc analysis of data from a randomized trial of thymectomy in MG (Thymectomy Trial in Non-Thymomatous Myasthenia Gravis Patients Receiving Prednisone Therapy [MGTX]). MGTX was a multicenter, randomized, rater-blinded 3-year trial that was followed by a voluntary 2-year extension for patients with acetylcholine receptor (AChR) antibody-positive MG without thymoma. Patients were randomized 1:1 to thymectomy plus prednisone vs prednisone alone. Participants were age 18-65 years at enrollment with disease duration less than 5 years. All patients received oral prednisone titrated up to 100 mg on alternate days until they achieved MMS, which prompted a standardized prednisone taper as long as MMS was maintained. The achievement rate of sustained MMS (no symptoms of MG for 6 months) with complete withdrawal of prednisone was compared between the thymectomy plus prednisone and prednisone alone groups.

RESULTS

Patients with MG in the thymectomy plus prednisone group achieved sustained MMS with complete withdrawal of prednisone more frequently (64% vs 38%) and quickly compared to the prednisone alone group (median time 30 months vs no median time achieved, p < 0.001) over the 5-year study period. Prednisone-associated adverse symptoms were more frequent in the prednisone alone group and distress level increased with higher doses of prednisone.

CONCLUSIONS

Thymectomy benefits patients with MG by increasing the likelihood of achieving sustained MMS with complete withdrawal of prednisone.

CLINICALTRIALSGOV IDENTIFIER

NCT00294658.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that for patients with generalized MG with AChR antibody, those receiving thymectomy plus prednisone are more likely to attain sustained MMS and complete prednisone withdrawal than those on prednisone alone.

A Phase 3 Multicenter, Prospective, Open-Label Efficacy and Safety Study of Immune Globulin (Human) 10% Caprylate/Chromatography Purified in Patients with Myasthenia Gravis Exacerbations

BACKGROUND

Myasthenia gravis (MG) is an autoimmune disorder affecting neuromuscular transmission. Exacerbations may involve increasing bulbar weakness and/or sudden respiratory failure, both of which can be critically disabling. Management of MG exacerbations includes plasma exchange and intravenous immunoglobulin (IVIG); they are equally effective, but patients experience fewer side effects with IVIG. The objective of this study was to assess the efficacy and safety of immune globulin caprylate/chromatography purified (IGIV-C) in subjects with MG exacerbations.

METHODS

This prospective, open-label, non-controlled 28-day clinical trial was conducted in adults with MG Foundation of America class IVb or V status. Subjects received IGIV-C 2 g/kg over 2 consecutive days (1 g/kg/day) and were assessed for efficacy/safety on Days 7, 14, 21, and 28. The primary efficacy endpoint was the change from Baseline in quantitative MG (QMG) score to Day 14. Secondary endpoints of clinical response, Baseline to Day 14, included at least a 3-point decrease in QMG and MG Composite and a 2-point decrease in MG-activities of daily living (MG-ADL).

RESULTS

Forty-nine subjects enrolled. The change in QMG score at Day 14 was significant (p < 0.001) in the Evaluable (-6.4, n = 43) and Safety (-6.7, n = 49) populations. Among evaluable subjects, Day 14 response rates were 77, 86, and 88% for QMG, MG Composite, and MG-ADL, respectively. IGIV-C showed good tolerability with no serious adverse events.

CONCLUSIONS

The results of this study show that IGIV-C was effective, safe, and well tolerated in the treatment of MG exacerbations.

Peripheral neuropathy in HIV patients on antiretroviral therapy: Does it impact function?

HIV-associated distal sensory polyneuropathy (DSP), with or without neuropathic symptoms, can develop after anti-retroviral therapy (ART). Symptoms frequently involve small fibres but reports on autonomic dysfunction in HIV-DSP are sparse. We studied an HIV-infected cohort after 5 years of ART, and report on the frequency and severity of autonomic symptoms and the impact of DSP on everyday function. This cross-sectional study comprised of participants from a community-based South African HIV-clinic. The Brief Peripheral Neuropathy Screen and reduced Total Neuropathy Score evaluated neuropathic symptoms/signs. DSP was defined as ≥2 symmetrical DSP-signs, and symptomatic DSP when accompanied by neuropathic symptoms. Autonomic symptoms questionnaires, heart rate variability and postural blood pressure changes were assessed. The Lower Extremity Functional Scale (LEFS) was completed. The 67 participants had a median age of 42 years and median ART exposure of 7 years with viral suppression in 84%. Most (81%) met our criteria for DSP and 36% had additional neuropathic symptoms. Autonomic symptoms and signs (above normative values) were present in 15% and more likely in those with symptomatic DSP (P < .001). Participants with DSP, even without symptoms, had lower LEFS scores (P ≤ .039) than those without. HIV-DSP is prevalent and impacts on daily living.

A review of the histopathological findings in myasthenia gravis: Clues to the pathogenesis of treatment-resistance in extraocular muscles

In myasthenia gravis autoantibodies target components of the neuromuscular junction causing variable degrees of weakness. In most cases, autoantibodies trigger complement-mediated endplate damage and extraocular muscles may be most susceptible. A proportion of MG cases develop treatment-resistant ophthalmoplegia. We reviewed publications spanning 65 years reporting the histopathological findings in the muscles and extraocular muscles of myasthenic patients to determine whether pathological changes in extraocular muscles differ from non-ocular muscles. As extraocular muscles represent a unique muscle allotype we also compared their histopathology in myasthenia to those in strabismus. We found that in myasthenia gravis, the non-ocular muscles frequently demonstrate neurogenic changes regardless of myasthenic serotype. Mitochondrial stress/damage was also frequent in myasthenic muscles and possibly more evident in muscle-specific kinase antibody-positive MG. Although myasthenia-associated paralysed extraocular muscles demonstrated prominent fibro-fatty replacement and mitochondrial alterations, these features appeared commonly in paralysed extraocular muscles of any cause. We postulate that extraocular muscles may be more susceptible than limb muscles to poor contractility as a consequence of myasthenia, resulting in a cascade of atrophy signaling pathways and altered mitochondrial homeostasis which contribute to the tipping point in developing treatment-resistant myasthenic ophthalmoplegia. Early strategies to improve force generation in extraocular muscles are critical.

Using Whole Genome Sequencing in an African Subphenotype of Myasthenia Gravis to Generate a Pathogenetic Hypothesis

Myasthenia gravis (MG) is a rare, treatable antibody-mediated disease which is characterized by muscle weakness. The pathogenic antibodies are most frequently directed at the acetylcholine receptors (AChRs) at the skeletal muscle endplate. An ophthalmoplegic subphenotype of MG (OP-MG), which is characterized by treatment resistant weakness of the extraocular muscles (EOMs), occurs in a proportion of myasthenics with juvenile symptom onset and African genetic ancestry. Since the pathogenetic mechanism(s) underlying OP-MG is unknown, the aim of this study was to use a hypothesis-generating genome-wide analysis to identify candidate OP-MG susceptibility genes and pathways. Whole genome sequencing (WGS) was performed on 25 AChR-antibody positive myasthenic individuals of African genetic ancestry sampled from the phenotypic extremes: 15 with OP-MG and 10 individuals with control MG (EOM treatment-responsive). Variants were called according to the Genome Analysis Toolkit (GATK) best practice guidelines using the hg38 reference genome. In addition to single variant association analysis, variants were mapped to genes (±200 kb) using VEGAS2 to calculate gene-based test statistics and HLA allele group assignment was inferred through "best-match" alignment of reads against the IMGT/HLA database. While there were no single variant associations that reached genome-wide significance in this exploratory sample, several genes with significant gene-based test statistics and known to be expressed in skeletal muscle had biological functions which converge on muscle atrophy signaling and myosin II function. The closely linked HLA-DPA1 and HLA-DPB1 genes were associated with OP-MG subjects (gene-based p < 0.05) and the frequency of a functional A > G SNP (rs9277534) in the HLA-DPB1 3'UTR, which increases HLA-DPB1 expression, differed between the two groups (G-allele 0.30 in OP-MG vs. 0.60 in control MG; p = 0.04). Furthermore, we show that rs9277534 is an HLA-DBP1 expression quantitative trait locus in patient-derived myocytes (p < 1 × 10^-3). The application of a SNP to gene to pathway approach to this exploratory WGS dataset of African myasthenic individuals, and comparing dichotomous subphenotypes, resulted in the identification of candidate genes and pathways that may contribute to OP-MG susceptibility. Overall, the hypotheses generated by this work remain to be verified by interrogating candidate gene and pathway expression in patient-derived extraocular muscle.

Long-term effect of thymectomy plus prednisone versus prednisone alone in patients with non-thymomatous myasthenia gravis: 2-year extension of the MGTX randomised trial

BACKGROUND

The Thymectomy Trial in Non-Thymomatous Myasthenia Gravis Patients Receiving Prednisone (MGTX) showed that thymectomy combined with prednisone was superior to prednisone alone in improving clinical status as measured by the Quantitative Myasthenia Gravis (QMG) score in patients with generalised non-thymomatous myasthenia gravis at 3 years. We investigated the long-term effects of thymectomy up to 5 years on clinical status, medication requirements, and adverse events.

METHODS

We did a rater-blinded 2-year extension study at 36 centres in 15 countries for all patients who completed the randomised controlled MGTX and were willing to participate. MGTX patients were aged 18 to 65 years at enrolment, had generalised non-thymomatous myasthenia gravis of less than 5 years' duration, had acetylcholine receptor antibody titres of 1·00 nmol/L or higher (or concentrations of 0·50-0·99 nmol/L if diagnosis was confirmed by positive edrophonium or abnormal repetitive nerve stimulation, or abnormal single fibre electromyography), had Myasthenia Gravis Foundation of America Clinical Classification Class II-IV disease, and were on optimal anticholinesterase therapy with or without oral corticosteroids. In MGTX, patients were randomly assigned (1:1) to either thymectomy plus prednisone or prednisone alone. All patients in both groups received oral prednisone at doses titrated up to 100 mg on alternate days until they achieved minimal manifestation status. The primary endpoints of the extension phase were the time-weighted means of the QMG score and alternate-day prednisone dose from month 0 to month 60. Analyses were by intention to treat. The trial is registered with ClinicalTrials.gov, number NCT00294658. It is closed to new participants, with follow-up completed.

FINDINGS

Of the 111 patients who completed the 3-year MGTX, 68 (61%) entered the extension study between Sept 1, 2009, and Aug 26, 2015 (33 in the prednisone alone group and 35 in the prednisone plus thymectomy group). 50 (74%) patients completed the 60-month assessment, 24 in the prednisone alone group and 26 in the prednisone plus thymectomy group. At 5 years, patients in the thymectomy plus prednisone group had significantly lower time-weighted mean QMG scores (5·47 [SD 3·87] vs 9·34 [5·08]; p=0·0007) and mean alternate-day prednisone doses (24 mg [SD 21] vs 48 mg [29]; p=0·0002) than did those in the prednisone alone group. 14 (42%) of 33 patients in the prednisone group, and 12 (34%) of 35 in the thymectomy plus prednisone group, had at least one adverse event by month 60. No treatment-related deaths were reported during the extension phase.

INTERPRETATION

At 5 years, thymectomy plus prednisone continues to confer benefits in patients with generalised non-thymomatous myasthenia gravis compared with prednisone alone. Although caution is appropriate when generalising our findings because of the small sample size of our study, they nevertheless provide further support for the benefits of thymectomy in patients with generalised non-thymomatous myasthenia gravis.

FUNDING

National Institutes of Health, National Institute of Neurological Disorders and Stroke.

Profiling of patient-specific myocytes identifies altered gene expression in the ophthalmoplegic subphenotype of myasthenia gravis

Background

While extraocular muscles are affected early in myasthenia gravis (MG), but respond to treatment, we observe a high incidence of treatment-resistant ophthalmoplegia (OP-MG) among MG subjects with African genetic ancestry. Previously, using whole exome sequencing, we reported potentially functional variants which associated with OP-MG. The aim of this study was to profile the expression of genes harbouring the OP-MG associated variants using patient-derived subphenotype-specific ‘myocyte’ cultures.

Methods

From well-characterised MG patients we developed the ‘myocyte’ culture models by transdifferentiating dermal fibroblasts using an adenovirus expressing MyoD. These myocyte cultures were treated with homologous acetylcholine receptor antibody-positive myasthenic sera to induce muscle transcripts in response to an MG stimulus. Gene expression in myocytes derived from OP-MG (n = 10) and control MG subjects (MG without ophthalmoplegia; n = 6) was quantified using a custom qPCR array profiling 93 potentially relevant genes which included the putative OP-MG susceptibility genes and other previously reported genes of interest in MG and experimental autoimmune myasthenia gravis (EAMG).

Results

OP-MG myocytes compared to control MG myocytes showed altered expression of four OP-MG susceptibility genes (PPP6R2, CANX, FAM136A and FAM69A) as well as several MG and EAMG genes (p < 0.05). A correlation matrix of gene pair expression levels revealed that 15% of gene pairs were strongly correlated in OP-MG samples (r > 0.78, p < 0.01), but not in control MG samples. OP-MG susceptibility genes and MG-associated genes accounted for the top three significantly correlated gene pairs (r ≥ 0.98, p < 1 × 10^− 6) reflecting crosstalk between OP-MG and myasthenia pathways, which was not evident in control MG cells. The genes with altered expression dynamics between the two subphenotypes included those with a known role in gangliosphingolipid biosynthesis, mitochondrial metabolism and the IGF1-signalling pathway.

Conclusion

Using a surrogate cell culture model our findings suggest that muscle gene expression and co-expression differ between OP-MG and control MG individuals. These findings implicate pathways not previously considered in extraocular muscle involvement in myasthenia gravis and will inform future studies.

Electronic supplementary material

The online version of this article (10.1186/s13023-019-1003-y) contains supplementary material, which is available to authorized users.

Vibrotactile sensitivity of patients with HIV-related sensory neuropathy: An exploratory study

BACKGROUND

HIV-associated distal polyneuropathy (HIV-PN) affects large and small sensory nerve fibers and can cause tactile insensitivity. This exploratory study forms part of an effort to apply subsensory electrical nerve stimulation (SENS) to improve tactile sensitivity of patients with HIV-PN. This work presented an opportunity to use a robust protocol to quantitatively describe the vibrotactile sensitivity of individuals with HIV-PN on effective antiretroviral therapy (ART) and correlate these findings with commonly used clinical vibration testing and scoring grades.

METHODS

The vibration perception thresholds (VPTs) of 20 patients with HIV-PN at three vibration frequencies (25, 50, and 128 Hz) were measured. We compare the vibration perception threshold (VPT) outcomes to an age- and gender-matched control cohort. We further correlated VPT findings with 128 Hz tuning fork (TF) assessments performed on the HIV-PN participants, accrued as part of a larger study. HIV-PN was defined as having at least one distal symmetrical neuropathic sign, although 18 of 20 had at least two neuropathic signs.

CONCLUSIONS

HIV-PN participants were found to have lower VPT sensitivity than controls for all three vibration frequencies, and VPT was more sensitive at higher vibration frequencies for both HIV-PN and controls. VPT sensitivity was reduced with older age. Years on ART was correlated with VPT-25 Hz but not with VPT in general. Notably, VPT sensitivity did not correlate with the clinically used 128 Hz TF severity grades. Outcomes of tests for interaction with vibration frequency suggest that HIV-PN pathology does not affect all mechanoreceptors similarly.

Exome sequencing identifies novel dysferlin mutation in a family with pauci-symptomatic heterozygous carriers

BACKGROUND

We investigated a South African family of admixed ancestry in which the first generation (G1) developed insidious progressive distal to proximal weakness in their twenties, while their offspring (G2) experienced severe unexpected symptoms of myalgia and cramps since adolescence. Our aim was to identify deleterious mutations that segregate with the affected individuals in this family.

METHODS

Exome sequencing was performed on five cases, which included three affected G1 siblings and two pauci-symptomatic G2 offspring. As controls we included an unaffected G1 sibling and a spouse of one of the G1 affected individuals. Homozygous or potentially compound heterozygous variants that were predicted to be functional and segregated with the affected G1 siblings, were further evaluated. Additionally, we considered variants in all genes segregating exclusively with the affected (G1) and pauci-symptomatic (G2) individuals to address the possibility of a pseudo-autosomal dominant inheritance pattern in this family.

RESULTS

All affected G1 individuals were homozygous for a novel truncating p.Tyr1433Ter DYSF (dysferlin) mutation, with their asymptomatic sibling and both pauci-symptomatic G2 offspring carrying only a single mutant allele. Sanger sequencing confirmed segregation of the variant. No additional potentially contributing variant was found in the DYSF or any other relevant gene in the pauci-symptomatic carriers.

CONCLUSION

Our finding of a truncating dysferlin mutation confirmed dysferlinopathy in this family and we propose that the single mutant allele is the primary contributor to the neuromuscular symptoms seen in the second-generation pauci-symptomatic carriers.

The functionality of African-specific variants in the TGFB1 regulatory region and their potential role in HIVAN

BACKGROUND

Transcription of transforming growth factor beta-1 (TGF-β1) is regulated by a polymorphic promoter region containing African-specific single nucleotide polymorphisms (SNPs). Some of these SNPs have higher frequencies among Southern Africans compared to other African populations and their functionality has only been partially studied. Due to the high prevalence of HIV-associated nephropathy (HIVAN) in Africans we hypothesized that functional African TGFB1-promoter SNPs may contribute to HIVAN pathogenesis.

METHODS

The functionality of the TGFB1 -1347 C>T variant and African-specific variants (-1287 G>A, -1154 C>T, -387 C>T and -14 G>A) were examined by measuring reporter gene expression in kidney and fibroblast cell lines co-transfected with TGFB1-promoter constructs and an HIV-Tat expression vector. TGF-β1 immunohistochemical staining was performed on kidney biopsies with HIVAN (n = 18) and compared to control biopsies without HIVAN or tubulointerstitial disease (n = 12) using semi-quantitative and digital image analysis. HIVAN cases were genotyped for TGFB1 -1347 and -387 SNP variants.

RESULTS

TGFB1-promoter haplotypes containing the African -387 T-allele resulted in ~ five-fold repression of TGFB1-promoter activity compared to -387 C haplotypes (p ≤ 0.024). HIV-Tat upregulated TGFB1-promoter activity for haplotypes containing -1347 T and -387 T in transfected renal cells (≈ 1.6-fold; p ≤ 0.030) and fibroblasts (≈ 1.3-fold; p ≤ 0.016). The renal interstitium from HIVAN biopsies, compared to HIV-positive and -negative controls, differed in the semi-quantitative TGF-β1 staining and digital optical density analyses. The TGFB1 -1347 and -387 genotypes in HIVAN cases were similar to population controls.

CONCLUSION

African-specific haplotypes lower TGFB1-promoter activity and expression levels and HIV-Tat upregulates TGFB1 promoter activity irrespective of the haplotype.

Evolution of sensory neuropathy after initiation of antiretroviral therapy

INTRODUCTION

We studied the evolution of sensory neuropathy after antiretroviral therapy (ART) in human immunodeficiency virus-infected South Africans.

METHODS

Enrolment commenced before ART with 6-monthly follow-ups for 24 months. Symptomatic distal sensory polyneuropathy (SDSP) was defined as one symptom and sign. Symptom/sign scores were compared between visits.

RESULTS

We enrolled 184 participants. Pre-ART, 16% had SDSP. After 18 months of ART, pain prevalence decreased in those with pre-ART SDSP (odds ratio [OR], 0.09; 95% confidence interval [95%CI], 0.03-0.29). Symptoms improved in 50% ever experiencing pain (mean improvement = 4.5 on 11-point scale). Participants SDSP-free pre-ART developed SDSP at a rate of 18 per 100 person-years. After 24 months (n = 102), 18% had SDSP. Stavudine (60% of cohort) did not predict incident SDSP, but associated with increased prevalence of reduced/absent reflexes at 18 months (OR, 2.24; 95% CI, 1.08-4.65).

DISCUSSION

Painful symptoms improved during ART. Evolving sensory neuropathy was due to increasing small and large fiber dysfunction. Muscle Nerve 57: 371-379, 2018.

IgG-specific cell-based assay detects potentially pathogenic MuSK-Abs in seronegative MG

OBJECTIVE

To increase the detection of MuSK-Abs using a CBA and test their pathogenicity.

METHODS

Sera from 69 MuSK-RIA-positive patients with myasthenia gravis (MG) (Definite MuSK-MG), 169 patients negative for MuSK-RIA and AChR-RIA (seronegative MG, SNMG), 35 healthy individuals (healthy controls, HCs), and 16 NMDA receptor-Ab-positive (NMDAR-Ab) disease controls were tested for binding to MuSK on a CBA using different secondary antibodies.

RESULTS

Initially, in addition to 18% of SNMG sera, 11% of HC and 19% of NMDAR-Ab sera showed positive binding to MuSK-transfected cells; this low specificity was due to anti-IgG(H+L) detection of IgM bound nonspecifically to MuSK. Using an IgG Fc gamma-specific secondary antibody, MuSK-Abs were detected by CBA in 68/69 (99%) of Definite MuSK-MG, 0/35 HCs, 0/16 NMDAR-Ab, and 14/169 (8%) of SNMG sera, providing increased sensitivity with high specificity. The RIA-negative, CBA-positive MuSK-IgG sera, but not IgM-MuSK-binding sera, reduced agrin-induced AChR clustering in C2C12 myotubes, qualitatively similar to RIA-positive MuSK-Abs.

CONCLUSIONS

An IgG-specific MuSK-CBA can reliably detect IgG MuSK-Abs and increase sensitivity. In the MuSK-CBA, IgG specificity is essential. The positive sera demonstrated pathogenic potential in the in vitro AChR-clustering assay, although less effective than Definite MuSK-MG sera, and the patients had less severe clinical disease. Use of IgG-specific secondary antibodies may improve the results of other antibody tests.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that an IgG-specific MuSK-CBA identifies patients with MG.

Exome sequencing identifies targets in the treatment-resistant ophthalmoplegic subphenotype of myasthenia gravis

Treatment-resistant ophthalmoplegia (OP-MG) is not uncommon in individuals with African genetic ancestry and myasthenia gravis (MG). To identify OP-MG susceptibility genes, extended whole exome sequencing was performed using extreme phenotype sampling (11 OP-MG vs 4 control-MG) all with acetylcholine receptor-antibody positive MG. This approach identified 356 variants that were twice as frequent in OP-MG compared to control-MG individuals. After performing probability test estimates and filtering variants according to those 'suggestive' of association with OP-MG (p < 0.05), only three variants remained which were expressed in extraocular muscles. Validation in 25 OP-MG and 50 control-MG cases supported the association of DDX17_delG (p = 0.014) and SPTLC3_insACAC (p = 0.055) with OP-MG, but ST8SIA1_delCCC could not be verified by Sanger sequencing. A parallel approach, using a semantic model informed by current knowledge of MG-pathways, identified an African-specific interleukin-6 receptor (IL6R) variant, IL6R c.*3043 T>C, that was more frequent in OP-MG compared to control-MG cases (p = 0.069) and population controls (p = 0.043). A weighted genetic risk score, derived from the odds ratios of association of these variants with OP-MG, correlated with the OP-MG phenotype as opposed to control MG. This unbiased approach implicates several potentially functional gene variants in the gangliosphingolipid and myogenesis pathways in the development of the OP-MG subphenotype.

Characteristics Of acetylcholine-receptor-antibody-negative myasthenia gravis in a South African cohort

INTRODUCTION

In this study we determined the frequencies of antibodies (Abs) directed against muscle-specific kinase (MuSK) and lipoprotein receptor-related protein 4 (LRP4) in the sera of a South African cohort with acetylcholine receptor (AChR)-antibody-negative generalized MG and determined outcomes to therapies.

METHODS

Sera negative by commercial AChR radioimmunoassay (RIA) were tested by MuSK RIA (n = 30; 2006-2012) and AChR, MuSK, and LRP4 RIA with or without cell-based assays (CBA) (n = 53; 2012-2015).

RESULTS

AChR-Abs were detected in 4 of 53 and MuSK-Abs in 20 of 83 (24%) cases. Thirty-six of 53 (68%) were triple seronegative (triple-SNMG) for MuSK, AChR, and LRP4-Abs. When compared with triple-SNMG, individuals with MuSK-MG had a younger onset age (P = 0.008), a greater likelihood of African genetic ancestry (P = 0.008), and 4-fold higher odds of reaching MGFA grade IVB/V (P = 0.018), but were also 9-fold more likely to reach at least minimal manifestations status after ≥12 months of therapy (P = 0.003).

CONCLUSIONS

Individuals with African genetic ancestry and severe bulbar/respiratory AChR-Ab-negative MG are likely to have MuSK-MG, but most respond favorably to maintenance immunotherapies. Muscle Nerve 54: 1023-1029, 2016.

Randomized Trial of Thymectomy in Myasthenia Gravis

BACKGROUND

Thymectomy has been a mainstay in the treatment of myasthenia gravis, but there is no conclusive evidence of its benefit. We conducted a multicenter, randomized trial comparing thymectomy plus prednisone with prednisone alone.

METHODS

We compared extended transsternal thymectomy plus alternate-day prednisone with alternate-day prednisone alone. Patients 18 to 65 years of age who had generalized nonthymomatous myasthenia gravis with a disease duration of less than 5 years were included if they had Myasthenia Gravis Foundation of America clinical class II to IV disease (on a scale from I to V, with higher classes indicating more severe disease) and elevated circulating concentrations of acetylcholine-receptor antibody. The primary outcomes were the time-weighted average Quantitative Myasthenia Gravis score (on a scale from 0 to 39, with higher scores indicating more severe disease) over a 3-year period, as assessed by means of blinded rating, and the time-weighted average required dose of prednisone over a 3-year period.

RESULTS

A total of 126 patients underwent randomization between 2006 and 2012 at 36 sites. Patients who underwent thymectomy had a lower time-weighted average Quantitative Myasthenia Gravis score over a 3-year period than those who received prednisone alone (6.15 vs. 8.99, P<0.001); patients in the thymectomy group also had a lower average requirement for alternate-day prednisone (44 mg vs. 60 mg, P<0.001). Fewer patients in the thymectomy group than in the prednisone-only group required immunosuppression with azathioprine (17% vs. 48%, P<0.001) or were hospitalized for exacerbations (9% vs. 37%, P<0.001). The number of patients with treatment-associated complications did not differ significantly between groups (P=0.73), but patients in the thymectomy group had fewer treatment-associated symptoms related to immunosuppressive medications (P<0.001) and lower distress levels related to symptoms (P=0.003).

CONCLUSIONS

Thymectomy improved clinical outcomes over a 3-year period in patients with nonthymomatous myasthenia gravis. (Funded by the National Institute of Neurological Disorders and Stroke and others; MGTX ClinicalTrials.gov number, NCT00294658.).

Isoniazid exposure and pyridoxine levels in human immunodeficiency virus associated distal sensory neuropathy

SETTING

Distal sensory polyneuropathy (DSP) may manifest in human immunodeficiency virus (HIV) infected individuals before or after antiretroviral therapy (ART). DSP can also occur in response to isoniazid (INH); this can be prevented by pyridoxine supplementation. N-acetyltransferase 2 (NAT2) polymorphisms influence drug acetylation and possibly the risk for INH-associated DSP.

OBJECTIVE

To investigate the relationship between previous/current TB, pyridoxine deficiency and DSP in HIV-infected individuals enrolled in a government-sponsored HIV programme.

DESIGN

Neuropathy assessments were performed among 159 adults pre-ART and 12 and 24 weeks thereafter. DSP was defined as ⩾1 neuropathic symptom and sign. NAT2 genotypes predicted acetylation phenotype. Serum pyridoxine levels (PLP) were quantified at baseline and week 12.

RESULTS

DSP was present in 16% of individuals pre-ART and was associated with previous/current TB (P = 0.020). Over 50% were pyridoxine deficient (PLP < 25 nmol/l), despite supplementation with vitamin B complex supplements (2-4 mg/day pyridoxine). Those with a history of TB and pre-ART DSP were more likely to be pyridoxine deficient (P = 0.029), and slow/intermediate NAT2 phenotypes impacted on their PLP levels. Incident/worsening DSP after ART developed in 21% of the participants. PLP levels remained low after ART, particularly among those with prior TB, but without an association between DSP or NAT2 phenotypes.

CONCLUSION

Adequate pyridoxine supplementation before ART initiation should be prioritised, particularly in those with a history of TB or current TB.

Sensory neuropathy and metabolic risk factors in human immune deficiency virus infected South Africans receiving protease inhibitors

Background

Protease inhibitors (PI)s have been associated with distal sensory polyneuropathy (DSP) and metabolic complications in high-income countries. No data exist in Africans where second-line antiretroviral therapy (ART) often include PIs.

Method

We performed a cross-sectional study to assess the DSP frequency and metabolic risk factors in community-based South Africans taking ritonavir-boosted lopinavir as PI. Examination findings categorized subjects as having DSP (≥1 neuropathic sign) or symptomatic DSP [DSP with symptom(s)]. Fasting-state glucose and lipid profiles were assessed. We compared the ritonavir/lopinavir-group to a nested group on first-line ART [dideoxy-nucleoside reverse transcriptase inhibitors (d-drugs)] selected from a dataset collected at the same time and matched for d-drug exposure.

Results

The ritonavir/lopinavir-group (n = 86) consisted predominantly of women (84 %) with a median age of 36 years (IQR 32–41). The median current CD4+ count was 489 cells/μL (IQR 291–665). The median exposure time to ritonavir/lopinavir was 18 months (IQR 10–26) and to d-drugs, 24 months (IQR 16–38). DSP was present in 78 % and symptomatic DSP in 48 %; symptoms were most frequently of moderate intensity. Only age independently associated with DSP and symptomatic DSP (p = 0.08 and p = 0.04, respectively). None of the metabolic syndrome components showed associations with DSP or symptomatic DSP despite a trend towards hypertriglyceridemia overall. The ritonavir/lopinavir-group had less DSP compared to the d-drug only group (p = 0.002) but the frequency of symptomatic DSP was similar (p = 0.49).

Conclusion

Ritonavir-boosted lopinavir did not add additional risk to developing DSP in this community-based African cohort after a median of 18 months on second-line ART.

Electronic supplementary material

The online version of this article (doi:10.1186/s12981-015-0073-8) contains supplementary material, which is available to authorized users.

Sensory polyneuropathy in human immunodeficiency virus-infected patients receiving tuberculosis treatment

SETTING

Human immunodeficiency virus (HIV) infection and treatments for HIV infection and tuberculosis (TB) are associated with the risk of developing sensory polyneuropathy (SPN). Vitamin B6 and genetically determined slow isoniazid (INH) acetylation are believed to play key roles in the development of SPN in a TB treatment setting.

OBJECTIVE

To investigate slow acetylation and risk factors for SPN in HIV-infected patients receiving TB treatment, and establish vitamin B6 status and its association with SPN.

METHODS

HIV-infected in-patients were prospectively assessed after initiating TB treatment and vitamin B6 supplementation, and monthly during hospitalisation. SPN was defined as ≥1 symptom plus ≥1 sign. NAT2 genotyping predicted acetylation status, and plasma high performance liquid chromatography estimated vitamin B6 status. A survival analysis estimated hazard ratios (HRs) for SPN during TB treatment.

RESULTS

Of 116 participants, 56% had SPN at study entry. Participants developed SPN at a rate of 26/100 person-months (95%CI 18-35) during TB treatment, which was independently associated with slow acetylation (HR 2.5; 95%CI 1.1-5.9), as well as black race, previous TB and extra-pulmonary/disseminated TB. Vitamin B6 status was normal, irrespective of SPN.

CONCLUSIONS

Risk factors for SPN suggest a multi-factorial pathogenesis related to INH and other potential nervous system insults. SPN developed despite normal vitamin B6 status, suggesting other mechanisms of injury.

Neuropsychiatric symptoms in patients with thymoma-associated and non-thymoma myasthenia gravis

<p><strong>Background. </strong>Around 10 - 15% of patients with myasthenia gravis (MG) have a thymoma, and non-motor symptoms are more frequent in these patients. We hypothesised that neuropsychiatric symptoms would also be more frequent. </p><p><strong>Methods. </strong>A cross-sectional study of 30 consecutive MG patients attending a clinic at Groote Schuur Hospital, Cape Town, South Africa, was done over a 6-month period in 2010. Each patient underwent a series of single-blinded neuropsychiatric assessments, including the 16-item, self-reported Flanagan Quality of Life (QOL) scale, the Beck Depression Inventory second version, the Young Mania Rating Scale, the Hamilton Anxiety Rating Scale and the Brief Psychiatric Rating Scale (BPRS).  </p><p><strong>Results. </strong>The frequency and nature of neuropsychiatric symptoms were similar between thymoma (<em>n</em>=9) and non-thymoma (<em>n</em>=21) MG patients. Symptoms of moderate or severe depression and anxiety were present in around 30%. The severity of depression symptoms correlated with MG severity. Prednisone dosing was not associated with neuropsychiatric symptoms or QOL scores. Those with longer duration of MG were more likely to have higher scores on the BPRS and anxiety scales. Those with younger-onset MG had higher BPRS scores and a tendency to suicidal behaviour. </p><p><strong>Conclusion. </strong>Although no association with thyoma was found, this study shows that neuropsychiatric conditions may be underdiagnosed in patients with MG. Systematic depression screening should be done at outpatient clinics, particularly for those who developed symptoms at a young age, those with severe disease and those with a long duration of illness.</p>

Plasma cytokine profiles in HIV-1 infected patients developing neuropathic symptoms shortly after commencing antiretroviral therapy: a case-control study

BACKGROUND

In patients infected with human immunodeficiency virus 1 (HIV-1) neuropathic symptoms may develop within weeks of starting combination antiretroviral therapy (cART). This timing coincides with the occurrence of immune reconstitution inflammatory syndrome. Our objective was to investigate the longitudinal association of plasma cytokine and soluble receptor concentrations with incident neuropathic symptoms within 12 weeks of starting programme-based cART in a nested case-control study.

METHODS

One hundred and twenty adults without neuropathic symptoms and about to initiate cART were followed longitudinally for 24 weeks after cART initiation. Subjects were examined for peripheral neuropathy at baseline (pre-cART) and 2-, 4-, 12- and 24 weeks thereafter. Individuals developing neuropathic symptoms within 12 weeks of starting cART were matched in a nested case-control design with those remaining symptom-free for at least 24 weeks. Plasma was collected at each visit. Cytokines and soluble receptors were quantified using multiplex immunometric assays.

RESULTS

Incident neuropathic symptoms occurred in 32 (27%) individuals within 12 weeks of starting cART for the first time. Cytokine concentrations increased at 2 weeks, irrespective of symptom-status, returning to baseline concentrations at 12 weeks. Compared to the control group, the symptomatic group had higher baseline levels of interleukin-1 receptor (IL-1R)-antagonist. The symptomatic group also showed greater increases in soluble interleukin-2 receptor-alpha and tumour necrosis factor (TNF) receptor-II levels at week 2 and soluble interleukin-6 receptor levels at week 12. Ratios of pro-inflammatory- vs anti-inflammatory cytokines were higher for TNF-alpha/IL-4 (p = 0.022) and interferon-gamma/IL-10 (p = 0.044) in those developing symptoms. After 24 weeks of cART, the symptomatic group showed higher CD4+ counts (p = 0.002).

CONCLUSIONS

The initiation of cART in previously treatment naïve individuals was associated with a cytokine 'burst' between 2- and 4 weeks compared with pre-cART levels. Individuals developing neuropathic symptoms within 12 weeks of starting cART showed evidence of altered cytokine concentrations even prior to initiating cART, most notably higher circulating IL-1R-antagonist levels, and altered ratios of "pain-associated" cytokine and soluble receptors shortly after cART initiation.

Molecular characterisation of virus in the brains of patients with measles inclusion body encephalitis (MIBE)

BACKGROUND

During 2009/10 a major measles epidemic caused by genotype B3 occurred in South Africa. Measles inclusion body encephalitis (MIBE) was diagnosed in a number of highly immuno-compromised HIV patients. The diagnosis was based on typical clinical and MRI findings and positive measles virus PCR in brain or CSF.To characterize the brain virus, nucleoprotein, matrix, fusion and haemagglutinin genes from 4 cases was compared with virus from acutely infected patients.

METHODS

cDNA was synthesized using random primers and viral genes were amplified by nested RT-PCR. PCR products were sequenced in the forward and reverse direction and a contig of each gene was created. Sequences were aligned with reference sequences from GenBank and other local sequences.

RESULTS

Brain virus was very similar to the South African epidemic virus. Features characteristic of persistent measles virus in the brain were absent. Mutation frequency in brain virus was similar to epidemic virus and had the same substitution preference (U to C and C to U). The virus of 2 patients had the same L454W mutation in the fusion protein.

CONCLUSION

The brain virus was very similar to the epidemic strain. The relatively few mutations probably reflect the short time from infection to brain disease in these highly immuno-compromised patients.

Mitochondrial genomics and antiretroviral therapy-associated metabolic complications in HIV-infected Black South Africans: a pilot study

Studies suggest that mitochondrial DNA (mtDNA) haplogroups are associated with antiretroviral therapy (ART)-related metabolic complications and distal sensory polyneuropathy (DSP), but there have been few studies in persons of African descent. We explored such associations in South African adults. Clinical and laboratory data and DNA specimens from a cross-sectional study were used. Sequencing and Phylotree determined African mtDNA subhaplogroups. Wilcoxon and regression analyses determined associations between mtDNA subhaplogroups and ART-related complications. The 171 participants represented six major haplogroups: L0 (n=78), L1 (n=3), L2 (n=30), L3 (n=53), L4 (n=1), and L5 (n=6). Analyses were restricted to 161 participants representing L0, L2, and L3: 78% were female; the median age was 36 years. All had been exposed to thymidine analogues, 42% were on lopinavir/ritonavir (lopinavir/r), and 58% were on either efavirenz or nevirapine. Median (IQR) ART duration was 22 (14-36) months. Median fasting triglycerides were 1.60 (1.13-1.75) and 1.04 (0.83-1.45) mmol/liter among L3e1 (n=22) and other subhaplogroups, respectively (p=0.003). Subhaplogroup L3e1 [adjusted OR (aOR) 3.16 (95% CI: 1.11-8.96); p=0.03] and exposure to lopinavir/r [aOR 2.98 (95% CI: 1.02-8.96); p=0.05] were independently associated with hypertriglyceridemia, after adjusting for age, sex, and ART duration. There were no significant associations between mtDNA haplogroups and cholesterol, dysglycemia, hyperlactatemia, or lipoatrophy, or DSP. Subhaplogroup L3e1 and lopinavir/r exposure were independently associated with hypertriglyceridemia in black South Africans on ART. This is the first report to link an African mtDNA variant with hypertriglyceridemia. If replicated, these findings may provide new insights into host factors affecting metabolic complications.

Association of transforming growth factor β-1 (TGFB1) regulatory region polymorphisms with myasthenia gravis-related ophthalmoparesis

We investigated the association of an ophthalmoplegic complication developing in African myasthenia gravis (MG) subjects with polymorphisms in the regulatory region of TGFB1. We found significant associations with several putative functional single nucleotide polymorphisms (SNPs) (including two novel SNPs) that potentially alter transcription factor binding. Our data support a hypothesis that altered TGFB1 regulation may predispose individuals who harbour these SNPs to developing ophthalmoplegia as a result of increased TGF-β1 driven myofibrosis as a consequence to complement-mediated damage.

A single-blinded trial of methotrexate versus azathioprine as steroid-sparing agents in generalized myasthenia gravis

Background

Long-term immunosuppression is often required in myasthenia gravis (MG). There are no published trials using methotrexate (MTX) in MG. The steroid-sparing efficacy of azathioprine (AZA) has been demonstrated after 18-months of starting therapy. However, AZA is considered expensive in Africa. We evaluated the steroid-sparing efficacy of MTX (17.5 mg weekly) compared with AZA (2.5 mg/kg daily) in subjects recently diagnosed with generalized MG by assessing their average monthly prednisone requirements.

Methods

The primary outcome was the average daily prednisone requirement by month between the two groups. Prednisone was given at the lowest dose to manage MG symptoms and adjusted as required according to protocol. Single-blinded assessments were performed 3-monthly for 2-years to determine the quantitative MG score and the MG activities of daily living score in order to determine those with minimal manifestations of MG.

Results

Thirty-one subjects (AZA n = 15; MTX n = 16) satisfied the inclusion criteria but only 24 were randomized. Baseline characteristics were similar. There was no difference between the AZA- and MTX-groups in respect of prednisone dosing (apart from months 10 and 12), in quantitative MG Score improvement, proportions in sustained remission, frequencies of MG relapses, or adverse reactions and/or withdrawals. The MTX-group received lower prednisone doses between month 10 (p = 0.047) and month 12 (p = 0.039). At month 12 the prednisone dose per kilogram bodyweight in the MTX-group (0.15 mg/kg) was half that of the AZA-group (0.31 mg/kg)(p = 0.019).

Conclusions

This study provides evidence that in patients with generalized MG methotrexate is an effective steroid-sparing agent 10 months after treatment initiation. Our data suggests that in generalized MG methotrexate has similar efficacy and tolerability to azathioprine and may be the drug of choice in financially constrained health systems.

Trial registration

SANCTR:DOH-27-0411-2436

Polyneuropathy, anti-tuberculosis treatment and the role of pyridoxine in the HIV/AIDS era: a systematic review

Tuberculosis (TB) is increasing in incidence in certain parts of the world, particularly where there is a co-epidemic of human immunodeficiency virus/acquired immune-deficiency syndrome (HIV/AIDS), and it is associated with a significant degree of morbidity and mortality. One of the most common complications of anti-tuberculosis treatment is the development of a painful isoniazid (INH) associated polyneuropathy (PN), which is preventable with adequate pyridoxine supplementation. As PN is also the most frequent neurological complication associated with HIV infection, subjects who are HIV and TB co-infected may be at increased risk of developing PN. In this review, we explore current knowledge of anti-tuberculosis drug associated PN focusing on INH and its relationship to pyridoxine, as well as the additional impact of antiretroviral treatment and TB-HIV co-infection. It is evident that guidelines established for the prevention and treatment of this problem differ between industrialised and developing countries, and that further research is needed to define the optimum dosing of pyridoxine supplementation in populations where there is a significant burden of TB and HIV.

Polymyositis in African HIV-infected subjects

Polymyositis in HIV-infected subjects, clinically and pathologically resemble polymyositis in non-HIV-infected subjects. We report 14 consecutive HIV-associated polymyositis cases and compare specific features with 25 polymyositis cases seen over the same 6.5 year period. The HIV-polymyositis cases were all female and compared to the polymyositis cases were younger (median age 33 years, interquartile range (IQR) 29; 37 vs. 46 years, IQR 38; 52, p=0.002), and with 4-fold lower serum creatine kinase (CK) values (median 1158 vs. 5153IU/l; p=0.019). A definite clinical improvement on prednisone therapy was documented in eight HIV-polymyositis cases and one improved with anti-retroviral therapy alone. The recognition of HIV-polymyositis which is treatable, but may present with serum CK elevations less than twofolds above normal, is clinically relevant in sub-Saharan Africa where electromyography and muscle biopsies are not readily available.