Plasma proteomic analysis on neuropathic pain in idiopathic peripheral neuropathy patients

BACKGROUND AND AIMS

Why only half of the idiopathic peripheral neuropathy (IPN) patients develop neuropathic pain remains unknown. By conducting a proteomics analysis on IPN patients, we aimed to discover proteins and new pathways that are associated with neuropathic pain.

METHODS

We conducted unbiased mass-spectrometry proteomics analysis on blood plasma from 31 IPN patients with severe neuropathic pain and 29 IPN patients with no pain, to investigate protein biomarkers and protein-protein interactions associated with neuropathic pain. Univariate modeling was done with linear mixed modeling (LMM) and corrected for multiple testing. Multivariate modeling was performed using elastic net analysis and validated with internal cross-validation and bootstrapping.

RESULTS

In the univariate analysis, 73 proteins showed a p-value <.05 and 12 proteins showed a p-value <.01. None were significant after Benjamini-Hochberg adjustment for multiple testing. Elastic net analysis created a model containing 12 proteins with reasonable discriminatory power to differentiate between painful and painless IPN (false-negative rate 0.10, false-positive rate 0.18, and an area under the curve 0.75). Eight of these 12 proteins were clustered into one interaction network, significantly enriched for the complement and coagulation pathway (Benjamini-Hochberg adjusted p-value = .0057), with complement component 3 (C3) as the central node. Bootstrap validation identified insulin-like growth factor-binding protein 2 (IGFBP2), complement factor H-related protein 4 (CFHR4), and ferritin light chain (FTL), as the most discriminatory proteins of the original 12 identified.

INTERPRETATION

This proteomics analysis suggests a role for the complement system in neuropathic pain in IPN.

IgM Anti MAG± Peripheral Neuropathy (IMAGiNe) Study Protocol: An international, observational, prospective registry of patients with IgM M-protein Peripheral Neuropathies

BACKGROUND

International consensus on IgM ±anti-MAG±PNP (IgM PNP) is lacking. Despite increasing interest in clinical trials, validated disease-specific measures are needed to adequately capture limitations and changes over time. The IMAGiNe (IgM ± Anti-Myelin Associated Glycoprotein [MAG] peripheral Neuropathy) study surges as an international collaboration to create a standardized registry of patients with IgM ±anti-MAG PNP. The consortium, which currently consists of 11 institutions from 7 countries, presents here the IMAGiNe study design and protocol.

AIMS

Functional outcome measures will be constructed at the level of impairment, as well as activity and participation. We aim to describe the natural history of the cohort, the role of anti-MAG antibodies, the presence of clinical subtypes and potential biomarkers.

METHODS

The IMAGiNe study is a prospective, observational cohort study with a 3 years follow-up. At each assessment, researchers collect clinical data and subjects complete a list of pre-selected outcome measures. Among these, the 'Pre-Rasch-built Overall Disability Scale (Pre-RODS)' questionnaire will be submitted to Rasch analysis to assess classic and modern clinimetric requirements.

RESULTS

The final measures will include the IgM-PNP-specific RODS and Ataxia Rating Scale (IgM-PNP-ARS). Descriptions of the disease course, clinical heterogeneity, treatment regimes, variations in laboratory values and antibody titers, will help reach consensus on diagnosis and follow-up strategies.

CONCLUSION

The constructed interval scales will be cross-culturally valid and suitable for use in future clinical trials and daily practice. The ultimate goals are to improve functional individualized assessment, reach international consensus, and lay the foundations for successful designs in future studies.

[Loss of sight in the postpartum period]

BACKGROUND

Vision problems in case of pre-eclampsia or Hemolysis, Elevated Liver, Low Platelets syndrome (HELLP) occur in 25-40% of the cases. Ablatio retinae as a complication occurs in only 0,1-2%.

CASE DESCRIPTION

This article describes the case of a healthy 31-year-old woman who gave birth to her first child. A few hours after delivery she experienced vision loss. HELLP was diagnosed. Because of persistent vision loss combined with headache, the ophthalmologist and neurologist were consulted. A bilateral ablatio retinae as a complication of HELLP was diagnosed. Headache was most likely due to the side effect of nifedipine tablets, tension headache or a symptom of HELLP. Vision loss recovered spontaneously within a few weeks.

CONCLUSION

Ablatio retinae due to preeclampsia or HELLP is very rare. For all concerned health care providers it is essential to pay attention to vision loss being the first symptom of possible acute underlying diagnosis postpartum.

Vegetarians, Pescatarians and Flexitarians with Adequate Vitamin B12 Levels Have No Increased Risk of Polyneuropathy

BACKGROUND

In recent years, an increasing number of people adapt to a vegetarian, pescatarian or flexitarian dietary pattern that reduces the consumption of meat and fish. Although these dietary patterns have a risk for developing vitamin B12 deficiency associated polyneuropathy, it is unknown whether this risk is still increased when vitamin B12 levels are adequate.

OBJECTIVE

To examine whether a vegetarian, pescatarian or flexitarian dietary pattern is associated with an increased risk for idiopathic axonal polyneuropathy.

METHODS

We conducted a case-control study that included 256 idiopathic axonal polyneuropathy patients with adequate vitamin B12 blood levels and 630 controls. We used questionnaire data to determine the frequency of meat and fish consumption and defined dietary patterns.

RESULTS

The vegetarian (no meat or fish consumption) and the pescatarian (fish consumption, no meat consumption) dietary patterns showed no increased risk of axonal polyneuropathy. Frequency-effect analysis and quantity-effect analysis also did not show that a reduction of meat or fish consumption (flexitarian dietary pattern), either small or large, changed the risk of axonal polyneuropathy.

CONCLUSIONS

We did not find an increased risk for axonal polyneuropathy among people with a vegetarian, pescatarian or flexitarian diet and an adequate vitamin B12 level.

Clinical relevance of testing for metabolic vitamin B12 deficiency in patients with polyneuropathy

OBJECTIVE

Determine vitamin B12 threshold levels below which additional testing of methylmalonic acid (MMA) and/or homocysteine (Hcy) is useful to diagnose metabolic vitamin B12 deficiency in patients with polyneuropathy, and how vitamin B12, MMA and Hcy levels relate to the effect of supplementation therapy.

METHODS

In a retrospective cohort study of 331 patients with polyneuropathy, vitamin B12, MMA and Hcy were measured. Linear regression models with vitamin B12 as dependent and Hcy or MMA as covariate were compared, to assess which was best related to vitamin B12. Threshold vitamin B12 levels for metabolic deficiency (defined as elevatede metabolites) were determined using logistic regression with elevated metabolites as dependent and vitamin B12 as covariate.. A structured interview was conducted in 42 patients to evaluate response to vitamin B12 supplementation.

RESULTS

MMA was best related to vitamin B12. Using elevated MMA for metabolic deficiency, we found 90% sensitivity at a vitamin B12 threshold level <264 pmol/L (358 pg/mL) and 95% sensitivity at <304 pmol/L (412 pg/mL). Improvement after supplementation was reported by 19% patients and stabilization by 24%. 88% of patients with improvement and 90% with stabilization either had absolute deficiency (Vitamin B12 < 148 pmol/L) or metabolic deficiency (elevated MMA and vitamin B12 ≥ 148 pmol/L). There were no additional patients with improvement or stabilization with isolated elevated Hcy.

CONCLUSION

Testing of MMA has additional value in identifying patients with clinically relevant metabolic deficiency when vitamin B12 is below 304 pmol/L (412 pg/mL). Supplementation can be effective in patients with absolute and metabolic deficiency.

The role of de novo mutations in the development of amyotrophic lateral sclerosis

The genetic basis combined with the sporadic occurrence of amyotrophic lateral sclerosis (ALS) suggests a role of de novo mutations in disease pathogenesis. Previous studies provided some evidence for this hypothesis; however, results were conflicting: no genes with recurrent occurring de novo mutations were identified and different pathways were postulated. In this study, we analyzed whole-exome data from 82 new patient-parents trios and combined it with the datasets of all previously published ALS trios (173 trios in total). The per patient de novo rate was not higher than expected based on the general population (P = 0.40). We showed that these mutations are not part of the previously postulated pathways, and gene-gene interaction analysis found no enrichment of interacting genes in this group (P = 0.57). Also, we were able to show that the de novo mutations in ALS patients are located in genes already prone for de novo mutations (P < 1 × 10^-15 ). Although the individual effect of rare de novo mutations in specific genes could not be assessed, our results indicate that, in contrast to previous hypothesis, de novo mutations in general do not impose a major burden on ALS risk.

NEK1 variants confer susceptibility to amyotrophic lateral sclerosis

To identify genetic factors contributing to amyotrophic lateral sclerosis (ALS), we conducted whole-exome analyses of 1,022 index familial ALS (FALS) cases and 7,315 controls. In a new screening strategy, we performed gene-burden analyses trained with established ALS genes and identified a significant association between loss-of-function (LOF) NEK1 variants and FALS risk. Independently, autozygosity mapping for an isolated community in the Netherlands identified a NEK1 p.Arg261His variant as a candidate risk factor. Replication analyses of sporadic ALS (SALS) cases and independent control cohorts confirmed significant disease association for both p.Arg261His (10,589 samples analyzed) and NEK1 LOF variants (3,362 samples analyzed). In total, we observed NEK1 risk variants in nearly 3% of ALS cases. NEK1 has been linked to several cellular functions, including cilia formation, DNA-damage response, microtubule stability, neuronal morphology and axonal polarity. Our results provide new and important insights into ALS etiopathogenesis and genetic etiology.

Effect of Presymptomatic Body Mass Index and Consumption of Fat and Alcohol on Amyotrophic Lateral Sclerosis

IMPORTANCE

Because dietary intake may influence pathophysiologic mechanisms in sporadic amyotrophic lateral sclerosis (ALS), the association between premorbid dietary intake and the risk of sporadic ALS will provide insight into which mechanisms are possibly involved in ALS pathophogenesis.

OBJECTIVE

To systematically determine the association between premorbid dietary intake and the risk of sporadic ALS.

DESIGN, SETTING, AND PARTICIPANTS

A population-based case-control study was conducted in a general community setting in the Netherlands from January 1, 2006, to September 30, 2011. Analysis was conducted April 1, 2013, to November 15, 2014. All patients with a new diagnosis of possible, probable (laboratory supported), or definite ALS according to the revised El Escorial criteria were included and multiple sources were used to ensure complete case ascertainment. Of 986 eligible patients, 674 gave informed consent and returned a complete questionnaire; 2093 controls randomly selected from the general practitioners' registers and frequency matched to the patients for sex and age were included.

MAIN OUTCOMES AND MEASURES

We studied the premorbid intake of nutrients in association with the risk of ALS by using a 199-item food frequency questionnaire adjusted for confounding factors and corrected for multiple comparisons while minimizing recall bias.

RESULTS

Presymptomatic total daily energy intake in patients, reported as mean (SD), was significantly higher compared with controls (2258 [730] vs 2119 [619] kcal/day; P < .01), and presymptomatic body mass index (calculated as weight in kilograms divided by height in meters squared) was significantly lower in patients (25.7 [4.0] vs 26.0 [3.7]; P = .02). With values reported as odds ratio (95% CI), higher premorbid intake of total fat (1.14; 1.07-1.23; P < .001), saturated fat (1.43; 1.25-1.64; P < .001), trans-fatty acids (1.03; 1.01-1.05; P < .001), and cholesterol (1.08; 1.05-1.12; P < .001) was associated with an increased risk of ALS; higher intake of alcohol (0.91; 0.84-0.99; P = .03) was associated with a decreased risk of ALS. These associations were independent of total energy intake, age, sex, body mass index, educational level, smoking, and lifetime physical activity. No significant associations between dietary intake and survival were found.

CONCLUSIONS AND RELEVANCE

The combination of independent positive associations of a low premorbid body mass index and a high fat intake together with prior evidence from ALS mouse models transgenic for SOD1 and earlier reports on premorbid body mass index support a role for increased resting energy expenditure before clinical onset of ALS.

Prior medical conditions and the risk of amyotrophic lateral sclerosis

Sporadic amyotrophic lateral sclerosis (ALS) is believed to be a complex disease in which multiple exogenous and genetic factors interact to cause motor neuron degeneration. Elucidating the association between medical conditions prior to the first symptoms of ALS could lend support to the theory that specific subpopulations are at risk of developing ALS and provide new insight into shared pathogenic mechanisms. We performed a population-based case-control study in the Netherlands, including 722 sporadic ALS patients and 2,268 age and gender matched controls. Data on medical conditions and use of medication were obtained through a structured questionnaire. Multivariate analyses showed that hypercholesterolemia (OR 0.76, 95% CI 0.63-0.92, P = 0.006), the use of statins (OR 0.45, 95% CI 0.35-0.59, P = 1.86 × 10(-9)) or immunosuppressive drugs (OR 0.26, 95% CI 0.08-0.86, P = 0.03) were associated with a decreased risk of ALS. Head trauma was associated with an increased ALS susceptibility (OR 1.95, 95% CI 1.11-3.43, P = 0.02). No association was found with autoimmune diseases, cancer, psychiatric disorders or cardiovascular diseases, or survival. The lower frequency of hypercholesterolemia and less use of statins in ALS patients indicate a favorable lipid profile prior to symptom onset in at least a subpopulation of ALS. Prior head trauma is a risk factor for ALS and the significantly lower use of immunosuppressive drugs in ALS patients could suggest a protective effect. The identification of specific subpopulations at risk for ALS may provide clues towards possible pathogenic mechanisms.

Analysis of the KIFAP3 gene in amyotrophic lateral sclerosis: a multicenter survival study

Sporadic amyotrophic lateral sclerosis is a multifactorial disease of environmental and genetic origin. In a previous large multicenter genome wide study, common genetic variation in the Kinesin-Associated Protein 3 (KIFAP3) gene (rs1541160) was reported to have a significant effect on survival in amyotrophic lateral sclerosis patients. However, this could not be replicated in 3 smaller independent cohorts. We conducted a large multicenter multivariate survival analysis (n = 2362) on the effect of genetic variation in rs1541160. The previously reported beneficial genotype did not show a significant improvement in survival in this patient group.

Lifetime physical activity and the risk of amyotrophic lateral sclerosis

BACKGROUND

It has been hypothesised that physical activity is a risk factor for developing amyotrophic lateral sclerosis (ALS), fuelled by observations that professional soccer players and Gulf War veterans are at increased risk. In a population based study, we determined the relation between physical activity and risk of sporadic ALS, using an objective approach for assessing physical activity.

METHODS

636 sporadic ALS patients and 2166 controls, both population based, completed a semistructured questionnaire on lifetime history of occupations, sports and hobbies. To objectively compare the energy cost of a lifetime history of occupational and leisure time physical activities and to reduce recall bias, metabolic equivalent scores were assigned to each activity based on the Compendium of Physical Activities.

RESULTS

ALS patients had significantly higher levels of leisure time physical activity compared with controls (OR 1.08, 95% CI 1.02 to 1.14, p=0.008). No significant difference was found between patients and controls in the level of vigorous physical activities, including marathons and triathlons, or in occupational activity. Cumulative measures of physical activity in quartiles did not show a dose-response relationship.

CONCLUSIONS

An increased risk of ALS with higher levels of leisure time physical activity was found in the present study. The lack of association with occupational physical activity and the absence of a dose-response relationship strengthen the hypothesis that not increased physical activity per se but rather a genetic profile or lifestyle promoting physical fitness increases ALS susceptibility.

UBQLN2 in familial amyotrophic lateral sclerosis in The Netherlands

Recently it was discovered that mutations in the UBQLN2 gene were a cause of an X-linked dominant type of familial amyotrophic lateral sclerosis (ALS). We investigated the frequency of mutations in this gene in a cohort of 92 families with ALS in the Netherlands. Eight families were excluded because of male-to-male transmission. In the remaining 84 familial ALS cases no mutations were discovered in UBQLN2. Hence, UBQLN2 was not found to be a cause of familial ALS in the Netherlands.

CGG-repeat expansion in FMR1 is not associated with amyotrophic lateral sclerosis

Recently, repeat expansions in several genes have been shown to cause or be associated with amyotrophic lateral sclerosis (ALS). It has been demonstrated that an intronic hexanucleotide repeat expansion in C9ORF72 is a major cause of both familial (approximately 40%) and sporadic (approximately 5%) ALS, as well as frontotemporal dementia (FTD). In addition, a CAG-repeat expansion in exon 1 of ATXN2, otherwise known to cause spinocerebellar ataxia type 2, has been identified as a major risk factor for sporadic ALS. Intermediate repeat expansions in the fragile X mental retardation 1 (FMR1) gene (55-200 repeats) are known to cause fragile X-associated premature ovarian insufficiency [(FX)POI; female carriers] or fragile X-associated tremor/ataxia syndrome (FXTAS; male carriers) by CGG-mediated RNA toxicity. The present investigation involves screening FMR1 repeat length in 742 sporadic ALS patients and 792 matched controls. Our conclusion is that FMR1 repeat expansions are not associated with ALS.

High-flow extracranial-to-intracranial excimer laser-assisted nonocclusive anastomosis bypass for symptomatic carotid artery occlusion

BACKGROUND

A high-flow bypass is theoretically more effective than a conventional low-flow bypass in preventing strokes in patients with symptomatic carotid artery occlusion and a compromised hemodynamic state of the brain.

OBJECTIVE

To study the results of excimer laser-assisted nonocclusive anastomosis (ELANA) high-flow extracranial-to-intracranial (EC-IC) bypass surgery in these patients.

METHODS

Between August 1998 and May 2008, 24 patients underwent ELANA EC-IC bypass surgery because of transient ischemic attacks or minor ischemic stroke associated with carotid artery occlusion. We retrospectively collected information. Follow-up data were updated by structured telephone interviews between May and September 2008.

RESULTS

In all patients, the ELANA EC-IC bypass was patent at the end of surgery with a mean flow of 106 ± 41 mL/min. Within 30 days after the operation, 22 patients (92%) had no major complication, whereas 2 patients (8%) had a fatal intracerebral hemorrhage. During follow-up of a mean 4.4 ± 2.4 years, the bypass remained patent in 18 of the 22 surviving patients (82%) with a mean flow of 141 ± 59 mL/min. All patients with a patent bypass remained free of transient ischemic attacks and ischemic stroke. In 4 patients, the bypass occluded, accompanied by ipsilateral transient ischemic attacks in 2 patients, ipsilateral ischemic stroke in 1 patient, and contralateral ischemic stroke in another patient.

CONCLUSION

ELANA EC-IC bypass surgery in patients with carotid artery occlusion is technically feasible and results in cessation of ongoing transient ischemic attacks and minor ischemic strokes, but carries a risk of postoperative hemorrhage.

Population based epidemiology of amyotrophic lateral sclerosis using capture-recapture methodology

BACKGROUND

Variation in the incidence rate in epidemiological studies on amyotrophic lateral sclerosis (ALS) may be due to a small population size and under ascertainment of patients. The previously reported incidence decline in the elderly and a decrease in the male:female ratio in postmenopausal age groups have yet to be confirmed.

METHODS

ALS epidemiology in a large population based register in The Netherlands was studied between 1 January 2006 and 31 December 2009, and applied capture-recapture methodology in separate age and gender groups to adjust for the number of unobserved patients.

RESULTS

1217 incident patients were observed, and a capture-recapture incidence of 2.77 per 100 000 person-years (95% CI 2.63 to 2.91). Prevalence on 31 December 2008 was 10.32 per 100 000 individuals (95% CI 9.78 to 10.86). The incident cohort had a higher median age at onset (63.0 vs 58.1 years) and more bulbar onset patients (30.0% vs 19.1%) compared with the prevalent cohort. Incidence and prevalence peaked in the 70-74 year age group followed by a rapid decline in older age. The male:female ratio in the premenopausal age group (1.91, 95% CI 1.32 to 2.79) was not significantly higher than that in the postmenopausal age group (1.50, 95% CI 1.34 to 1.67).

CONCLUSION

The marked difference in patient characteristics between incident and prevalent cohorts underscores the importance of including incident patients when studying susceptibility or disease modifying factors in ALS. The incidence decline in the elderly may suggest that ALS is not merely the result of ageing. Absence of a significant postmenopausal drop in the male:female ratio suggests that the protective role of female sex hormones in ALS is limited.

Genome-wide association study identifies 19p13.3 (UNC13A) and 9p21.2 as susceptibility loci for sporadic amyotrophic lateral sclerosis

We conducted a genome-wide association study among 2,323 individuals with sporadic amyotrophic lateral sclerosis (ALS) and 9,013 control subjects and evaluated all SNPs with P < 1.0 x 10(-4) in a second, independent cohort of 2,532 affected individuals and 5,940 controls. Analysis of the genome-wide data revealed genome-wide significance for one SNP, rs12608932, with P = 1.30 x 10(-9). This SNP showed robust replication in the second cohort (P = 1.86 x 10(-6)), and a combined analysis over the two stages yielded P = 2.53 x 10(-14). The rs12608932 SNP is located at 19p13.3 and maps to a haplotype block within the boundaries of UNC13A, which regulates the release of neurotransmitters such as glutamate at neuromuscular synapses. Follow-up of additional SNPs showed genome-wide significance for two further SNPs (rs2814707, with P = 7.45 x 10(-9), and rs3849942, with P = 1.01 x 10(-8)) in the combined analysis of both stages. These SNPs are located at chromosome 9p21.2, in a linkage region for familial ALS with frontotemporal dementia found previously in several large pedigrees.