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Amyotrophic lateral sclerosis (ALS) is a genetically heterogeneous neurodegenerative syndrome hallmarked by adult-onset loss of motor neurons. We performed exome sequencing of 252 familial ALS (fALS) and 827 control individuals. Gene-based rare variant analysis identified an exome-wide significant enrichment of eight loss-of-function (LoF) mutations in TBK1 (encoding TANK-binding kinase 1) in 13 fALS pedigrees. No enrichment of LoF mutations was observed in a targeted mutation screen of 1,010 sporadic ALS and 650 additional control individuals. Linkage analysis in four families gave an aggregate LOD score of 4.6. In vitro experiments confirmed the loss of expression of TBK1 LoF mutant alleles, or loss of interaction of the C-terminal TBK1 coiled-coil domain (CCD2) mutants with the TBK1 adaptor protein optineurin, which has been shown to be involved in ALS pathogenesis. We conclude that haploinsufficiency of TBK1 causes ALS and fronto-temporal dementia. [ABSTRACT FROM AUTHOR]

There are no validated criteria for the diagnosis of sensory neuronopathy (SNN) yet. In a preliminary monocenter study a set of criteria relying on clinical and electrophysiological data showed good sensitivity and specificity for a diagnosis of probable SNN. The aim of this study was to test these criteria on a French multicenter study. 210 patients with sensory neuropathies from 15 francophone reference centers for neuromuscular diseases were included in the study with an expert diagnosis of non-SNN, SNN or suspected SNN according to the investigations performed in these centers. Diagnosis was obtained independently from the set of criteria to be tested. The expert diagnosis was taken as the reference against which the proposed SNN criteria were tested. The set relied on clinical and electrophysiological data easily obtainable with routine investigations. 9/61 (16.4 %) of non-SNN patients, 23/36 (63.9 %) of suspected SNN, and 102/113 (90.3 %) of SNN patients according to the expert diagnosis were classified as SNN by the criteria. The SNN criteria tested against the expert diagnosis in the SNN and non-SNN groups had 90.3 % (102/113) sensitivity, 85.2 % (52/61) specificity, 91.9 % (102/111) positive predictive value, and 82.5 % (52/63) negative predictive value. Discordance between the expert diagnosis and the SNN criteria occurred in 20 cases. After analysis of these cases, 11 could be reallocated to a correct diagnosis in accordance with the SNN criteria. The proposed criteria may be useful for the diagnosis of probable SNN in patients with sensory neuropathy. They can be reached with simple clinical and paraclinical investigations. [ABSTRACT FROM AUTHOR]

Cerebral aneurysms and arteropathies causing severe cerebrovascular events have been reported as rare complications in patients with late-onset Pompe disease. We investigated the frequency of cerebrovascular anomalies in six patients with late-onset Pompe disease followed at our institution. Clinical data collection and magnetic resonance angiography were performed as part of routine annual examinations. Four out of six patients had brain vascular anomalies including dolichoectasia of the basilar artery and ectasia of internal carotids. These patients also complained of gastrointestinal symptoms (chronic constipation and gastrointestinal reflux). Two patients had clinical signs related to the arteriopathy, including partial paralysis of the third cranial nerve and transient ischemic attacks. At 1 year follow-up, enzyme replacement therapy did not modify the size of cerebral vessels, but patients reported a marked improvement of intestinal symptoms. In conclusion, neurologists should be aware that intracranial artery abnormalities are not infrequent in patients with late-onset Pompe disease, and they should be specifically investigated in the presence of unexplained CNS symptoms. [ABSTRACT FROM AUTHOR]

A decrease in sensory nerve action potentials (SNAP) amplitude has been recently reported in some patients during the course of multifocal motor neuropathy with conduction blocks (MMNCB). It is not known if those patients have different clinical expression and disability when compared with typical MMNCB. Clinical, biological and electrophysiological assessments were performed in 15 patients fitting the diagnosis criteria of MMNCB, including normal SNAP amplitude at initial examination. Patients presenting with nerve entrapment or associated disease causative of sensory neuropathy were excluded. Median time of follow-up was 3 years (1–17 years). At the last examination, four patients had at least one SNAP amplitude below 50% of normal value. None had clinically objective sensory loss. Clinical and electrophysiological data obtained at the last examination were compared between patients with normal SNAP amplitude and patients with decreased SNAP amplitude. No difference between both population in term of age, sex, disease duration, anti-GM1 antibody titers, CSF data and number of conduction blocks was noted. In contrast, patients with decreased SNAP amplitude had worse overall neuropathy limitation scale (ONLS) scores (7 vs. 2; p = 0.02), a higher number of affected nerves (12.5 vs. 4; p = 0.018), a higher number of affected limb regions (6 vs. 2; p = 0.019) and lower median CMAP amplitude (2 mV vs. 6.5 mV; p = 0.04). They were all dependent on higher doses of IVIg (1.4 g/(kg 4 weeks vs. 0.6; p = 0.018). A reduction in SNAP amplitude during the course of MMNCB is associated with a more severe disease and a more prominent axonal loss. This result needs to be confirmed in a larger cohort. [ABSTRACT FROM AUTHOR]

ANT1, TWINKLE and POLG genes affect mtDNA stability and are involved in autosomal dominant PEO, while mutations in POLG are responsible for numerous clinical presentations, including autosomal recessive PEO, sensory ataxic neuropathy, dysarthria and ophthalmoparesis (SANDO), spino-cerebellar ataxia and epilepsy (SCAE) or Alpers syndrome. In this study, we report on the mutational analysis of ANT1, TWINKLE and POLG genes in 15 unrelated patients, using a dHPLC-based protocol. This series of patients illustrates the large array of clinical presentations associated with mtDNA stability defects, ranging from isolated benign PEO to fatal Alpers syndrome. A total of seven different mutations were identified in six of 15 patients (40%). Six different recessive mutations were found in POLG, one in TWINKLE while no mutation was identified in ANT1. Among the POLG mutations, three are novel and include two missense and one frameshift changes. Seventeen neutral changes and polymorphisms were also identified, including four novel neutral polymorphisms. Overall, this study illustrates the variability of phenotypes associated with mtDNA stability defects, increases the mutational spectrum of POLG variants and provides an efficient and reliable detection protocol for ANT1, TWINKLE and POLG mutational screening.European Journal of Human Genetics (2006) 14, 917–922. doi:10.1038/sj.ejhg.5201627; published online 26 April 2006 [ABSTRACT FROM AUTHOR]

Facioscapulohumeral muscular dystrophy (FSHD), an autosomal dominant neuromuscular disorder, has been causally related to deletion of tandemly arrayed 3.3 kb repeats (D4Z4) on chromosome 4q35. Although increased expression of several 4q35 genes has been reported, two recent studies dispute this, finding no significant changes in the transcriptional level of any of the 4q35 genes, among which is the heart and muscle-specific isoform of the adenine nucleotide translocator (ANT1). We found markedly increased levels of ANT1 protein in both unaffected and affected FSHD muscles in comparison to control healthy muscles. Comparative protein expression analysis between healthy, Duchenne muscular dystrophy, and FSHD muscle shows that proteins involved in mitochondrial function and protection from oxidative stress are also reproducibly and specifically modified in all FSHD muscles, including clinically unaffected muscles. Increased ANT1 expression and mitochondrial dysfunction may thus be initial events in FSHD pathogenesis and represent potential therapeutic targets. [ABSTRACT FROM AUTHOR]

There is a large body of evidence that free radical-mediated oxidative damage is involved in the pathogenesis of neurodegenerative disease. Although it is unlikely that markers of such damage will have any diagnostic value, they might be of considerable interest in following disease progression and monitoring the efficacy of different treatments. Among such markers, there is evidence for the elevation of peripheral malondialdehyde levels in several neurodegenerative diseases, including Parkinson's disease, amyotrophic lateral sclerosis and Alzheimer's disease. The measurement of malondialdehyde levels, which is both simple and cheap to perform, can and should be incorporated into future clinical trials. This will allow a clearer picture to emerge as to whether malondialdehyde can be considered as a marker for the evolution of these diseases. [ABSTRACT FROM AUTHOR]

The article discusses a study which described intracranial artery abnormalities in patients with late onset Pompe disease (LOPD) or glycogen storage disease type II. Topics include the causes and clinical characteristics of LOPD, the role of enzyme replacement therapy (ERT) in improving the condition of patient with LOPD, and an overview of the radiological data of the long-extended term follow-up of a cohort of LOPD Pome patients studied between 2006 and 2016.

A correction to the article "Molecular analysis of ANT1, TWINKLE and POLG in patients with multiple deletions or depletion of mitochondrial DNA by a dHPLC-based assay" that was published in a previous issue of the periodical is presented.