CSF neurofilament proteins as diagnostic and prognostic biomarkers for amyotrophic lateral sclerosis

Elevated cerebrospinal fluid (CSF), Neurofilament Light (NF-L) and phosphorylated Heavy (pNF-H) chain levels have been found in Amyotrophic Lateral Sclerosis (ALS), with studies reporting a correlation of both neurofilaments (NFs) with the disease progression. Here, we measured NF-L and pNF-H concentrations in the CSF of ALS patients from a single tertiary Center and investigated their relationship with disease-related variables. A total of 190 ALS patients (Bulbar, 29.9%; Spinal, 70.1%; M/F = 1.53) and 130 controls with mixed neurological diseases were recruited. Demographic and clinical variables were recorded, and ΔFS was used to rate the disease progression. Controls were divided into two cohorts: (1) patients with non-inflammatory neurological diseases (CTL-1); (2) patients with acute/subacute inflammatory diseases and tumors, expected to lead to significant axonal and tissue damage (CTL-2). For each patient and control, CSF was taken at the time of the diagnostic work-up and stored following the published guidelines. CSF NF-L and pNF-H were assayed with commercially available ELISA-based methods. Standard curves (from independent ELISA kits) were highly reproducible for both NFs, with a coefficient of variation < 20%. We found that CSF NF-L and pNF-H levels in ALS were significantly increased when compared to CTL-1 (NF-L: ALS, 4.7 ng/ml vs CTL-1, 0.61 ng/ml, p < 0.001; pNF-H: ALS, 1.7 ng/ml vs CTL-1, 0.03 ng/ml, p < 0.0001), but not to CTL-2. Analysis of different clinical and prognostic variables disclosed meaningful correlations with both NF-L and pNF-H levels. Our results, from a relatively large ALS cohort, confirm that CSF NF-L and pNF-H represent valuable diagnostic and prognostic biomarkers in ALS.     

Genetics of familial amyotrophic lateral sclerosis

The completion of the Human Genome Project, together with a better understanding of some of the emerging genetic patterns of human disease, has enabled a thorough examination of the most appropriate genetic models for amyotrophic lateral sclerosis (ALS). The pathology and epidemiology of ALS have been intensively studied since Adar, Charcot, and Duchenne first described the disease in the 1860 s. Results of genetic studies that have emerged over the past two decades have led to the identification of SOD1 as a well-established causative gene for ALS. However, the identification of SOD1 has not been followed up by the identification of other genes responsible for classic ALS. This leads to the speculation that more complex genetic mechanisms are involved than initially assumed. While mutations in single genes are still likely to constitute a small proportion of ALS cases, the genes responsible for ALS in families with clusters of two or three affected individuals, and more particularly in sporadic cases, are far from being determined. Multigenic, somatic mutation, and gene-environment models may all contribute to the genetic etiology of ALS. The challenge now lies in determining which models are the most appropriate to dissect out the genetic components involved. This research will ultimately aid in identifying the cumulative risk of developing ALS.     

Linkage analysis in familial amyotrophic lateral sclerosis

Familial amyotrophic lateral sclerosis (FALS) constitutes 5 to 10% of cases of ALS and, in most families, its inheritance is consistent with an autosomal dominant trait with age-dependent penetrance. The biochemical abnormality underlying the disorder is unknown. We analyzed DNA from 131 members of 6 multigenerational ALS families, which included 13 affected members, for genetic linkage to 39 expressed and DNA markers, using the techniques of 2-point linkage analysis, multilocus linkage analysis, and exclusion mapping. We identified FALS families with structures suitable for linkage, by computer simulation techniques. A DNA bank established to provide optimum use of available FALS families provided DNA from immortalized lymphoblast cell lines and frozen postmortem tissue. We could not link FALS to any of the markers studied, but excluded chromosome regions unlikely to be a locus of the FALS gene. With the help of this exclusion data, we will concentrate on regions of the human genome that remain unexcluded.     

Atypical forms of familial amyotrophic lateral sclerosis

Familial cases of A.L.S. are more frequent in young people. The course is short. There are some alterations of sensory pathways. However some atypical cases are known. Three patients had such clinical features: in the first case there was a progressive weakness of scapular girdle with neck muscles involvement. The second case was a progressive spinal amyotrophy. The last was a bulbar form. In all 3 cases there was an autosomal dominant inheritance, but the course was slow.     

TDP-43 mutation in familial amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder. Accumulating evidence has shown that 43kDa TAR-DNA-binding protein (TDP-43) is the disease protein in ALS and frontotemporal lobar degeneration. We previously reported a familial ALS with Bumina bodies and TDP-43-positive skein-like inclusions in the lower motor neurons; these findings are indistinguishable from those of sporadic ALS. In three affected individuals in two generations of one family, we found a single base-pair change from A to G at position 1028 in TDP-43, which resulted in a Gln-to-Arg substitution at position 343. Our findings provide a new insight into the molecular pathogenesis of ALS.     

Absence of p53: no effect in a transgenic mouse model of familial amyotrophic lateral sclerosis

Familial amyotrophic lateral sclerosis (ALS) has been linked in some families to dominantly inherited mutations in the gene encoding copper-zinc superoxide dismutase 1 (Cu-Zn SOD1). Transgenic mice expressing a mutant human Cu-Zn SOD1 (G93A) develop a dominantly inherited adult-onset paralytic disorder that replicates many of the clinical and pathological features of familial ALS. Increased p53 immunoreactivity has been reported in the motor cortex and spinal ventral horns of postmortem tissue from ALS patients. The nuclear phosphoprotein p53 is an important regulator of cellular proliferation, and increasing evidence supports the role of p53 in regulating cellular apoptosis. To assess the role of p53-mediated apoptosis in amyotrophic lateral sclerosis, mice deficient in both p53 alleles (p53-/-) were crossed with transgenic mice expressing the G93A mutant (G93A+), creating novel transgenic knockout mice. The animals (p53 +/+G93A+, p53+/-G93A+, p53-/-G93A+) were examined at regular intervals for cage activity, upper and lower extremity strength, and mortality. At 120 days from birth mice from each genotype were sacrificed, and L2-L3 anterior horn motor neurons were counted. There was no significant difference in time to onset of behavioral decline, mortality, or motor neuron degeneration between the different genotypes. Despite evidence that p53 plays an important role after acute neuronal injury, the current study suggests that p53 is not significantly involved in cell death in the G93A+ transgenic mouse model of familial ALS.     

Parental sex effect in familial amyotrophic lateral sclerosis

Since a parental sex effect has been reported in Huntington's disease, we looked to see whether a similar effect is apparent in adult (autosomal dominant) familial ALS. We analyzed the data for 145 patients, with an onset age range of 20 to 68 years and a known affected parent (AP), from 52 families described in the literature. There was a significant increase in the percentage of patients inheriting the gene from an affected mother as a function of the age at onset. There was also a significant correlation between AP and offspring age at onset only when the AP was the mother.     

Difficulties in distinguishing sporadic from familial amyotrophic lateral sclerosis

Mutations of the copperlzinc superoxide dismutase (SOD-1) gene are present in around 20% of patients with a family history of amyotrophic lateral sclerosis. The finding of these mutations in patients with sporadic amyotrophic lateral sclerosis is rare. We describe a family with amyotrophic lateral sclerosis associated with the SOD-1 mutation Asp 101 Asn. This mutation was previously described as occurring in a patient with sporadic disease. We discuss the difficulties in defining truly sporadic amyotrophic lateral sclerosis, and the consequent implications on the neurogenetic advice given to other family members.     

Cerebral lesions in familial amyotrophic lateral sclerosis and dementia

Summary In familial amyotrophic lateral sclerosis associated with dementia there was symmetrical involvement of the amygdala, insula, and fronto-temporal cortex. The cortical lesions were most severe in the superior frontal gyri and the infero-lateral temporal lobes, while the adjacent cingulate gyri and hippocampi were spared. One patient with dementia and another with slight mental abnormality had cerebral lesions which varied in extent, but were of the same type and pattern. Although the clinical and histological findings are variable, the disease seems to be a distinct entity, closely allied to amyotrophic lateral sclerosis, but also having features in common with Guamanian amyotrophic lateral sclerosis, and amyotrophic lateral sclerosis-dementia complex of sporadic occurrence.     

Absence of linkage of ABO blood group locus to familial tuberous sclerosis

A mutation leading to tuberous sclerosis was linked to the ABO blood group locus (9q34) on the long arm of chromosome 9. In an effort to confirm this assignment, nine multigenerational families with tuberous sclerosis, comprising 126 sampled individuals, were assessed for linkage of the ABO locus to tuberous sclerosis. Two-point linkage analysis and multilocus linkage analysis were used to evaluate linkage between tuberous sclerosis and the markers ABO, MCT136, and AblK2. Linkage of ABO to tuberous sclerosis was excluded for a distance of 20 centimorgans (cM) encompassing the region of the ABO locus. There was no evidence for genetic heterogeneity within this data set. Using 23 polymorphic markers, exclusion mapping demonstrated only a 1% probability that the tuberous sclerosis locus was on the distal short arm of chromosome 9 and provided no evidence in support of a tuberous sclerosis locus on the remainder of chromosome 9 including the area of the ABO locus.     

SOD1 and cognitive dysfunction in familial amyotrophic lateral sclerosis

Background   Sporadic Amyotrophic Lateral Sclerosis (sALS) is associated with frontotemporal dementia (ALS-FTD) or milder deficits of cognitive (predominantly executive) dysfunction (ALSCi) in some patients. Some forms of familial ALS (FALS) have a family history of FTD, ALS-FTD, or both, but there have been few reports of ALS-FTD in FALS patients with mutations of the gene superoxide dismutase-1 (SOD1 FALS). The aim of this study was to test the hypothesis that ALSCi may be found in non-SOD1 FALS, but that SOD1 FALS patients would show little or no evidence of cognitive change. Methods   A neuropsychological test battery was administered to 41 SALS patients, 35 control participants, 7 FALS patients with a SOD1 mutation (SOD1 FALS) and 10 FALS patients without a SOD1 mutation (non-SOD1 FALS). Results   Relative to control participants, non-SOD1 FALS patients had impaired performance on written verbal fluency and confrontation naming, and reported higher levels of executive behavioural problems. These deficits were absent in SOD1 FALS patients. SALS patients performed poorer than controls only on the Graded Naming Test. All ALS groups had higher levels of behavioural apathy and emotional lability than were found in control participants. Cognitive domains of memory, receptive language, and visuospatial perception were spared. Groups were matched for age, gender, premorbid full-scale IQ, anxiety and depression. Discussion   Individuals with SOD1 gene mutations are less likely to have significant cognitive changes compared to non-SOD1 FALS patients. Cognitive abnormalities in ALS are heterogeneous and may reflect underlying genetic variations rather than a simple spectrum of extra-motor involvement.     

Juvenile familial amyotrophic lateral sclerosis: four cases with long survival

Four cases are reported of juvenile familial amyotrophic lateral sclerosis (JFALS) with exceptionally long survival (mean=27 years), and consequent development of dementia. Subjects' mean age at onset was 15–7 years. Their clinical features and electrophysiological findings support the diagnosis. One subject's MRI scan showed severe atrophy to the cortex and brain stem; wallerian degeneration in the pyramidal pathway, as reported in other studies, could not be found. JFALS is characterized by the involvement of other neuronal systems not present in the adult form and by long survival after disease onset.     

Antibody response to arboviruses. Absence of increased response in amyotrophic lateral sclerosis and multiple sclerosis

Complement fixation and hemagglutination imhibition tests were conducted on the serums of patients with amyotrophic lateral sclerosis and multiple sclerosis using a variety of arboviral antigens. Seventy-eight complement fixation and 15 hemagglutination-inhibition viral antigens were used representing togaviruses, orbiviruses, rhadoviruses, bunyaviruses, arenaviruses, and several ungrouped agents. The serological results did not indicate any relationship between these viruses and either amyotrophic lateral sclerosis or multiple sclerosis.