Statins, diabetes mellitus and prognosis of amyotrophic lateral sclerosis: data from 501 patients of a population-based registry in southwest Germany

BACKGROUND AND PURPOSE

A wide variety of metabolic changes, including an increased incidence of diabetes mellitus (DM) and dyslipidaemia, has been described in amyotrophic lateral sclerosis (ALS). The aim of this study was to investigate the associations of statin use and history of DM with onset of disease and survival in patients with ALS.

METHODS

In all, 501 patients (mean age 65.2 ± 10.9 years; 58.5% male) from the ALS Registry Swabia recruited between October 2010 and April 2016 were included in this prospective cohort study. Data were collected using a standardized questionnaire.

RESULTS

Statin use (n = 65) was not associated with overall survival (P = 0.62). Age of ALS onset in patients with DM was 4.2 years later (95% confidence interval 1.3-7.2 years) than in patients without DM (P < 0.01). The overall survival of patients with high body mass index at study entry (>27.0 kg/m² , upper quartile, n = 127) was prolonged by more than 5 months compared to patients with low body mass index (<22.0 kg/m² , lower quartile, n = 123; P = 0.04).

CONCLUSIONS

This study supports the view that statin use is not associated with overall survival of ALS patients, suggesting that statins are not harmful and should not be discontinued in ALS. Furthermore, the delayed onset of ALS in patients with DM may mirror the potentially protective metabolic profile associated with type 2 DM. Consistently, this study provides further evidence that high body mass index is a positive prognostic factor in ALS.

Truncating mutations in FUS/TLS give rise to a more aggressive ALS-phenotype than missense mutations: a clinico-genetic study in Germany

BACKGROUND AND PURPOSE

Mutations in the FUS/TLS have been associated with amyotrophic lateral sclerosis (ALS) in a few percent of patients.

METHODS

We screened 184 familial (FALS) and 200 sporadic German patients with ALS for FUS/TLS mutations by sequence analysis of exons 5, 6 and 13-15. We compared the phenotypes of patients with different FUS/TLS mutations.

RESULTS

We identified three missense mutations p.K510R, p.R514G, p.R521H, and the two truncating mutations p.R495X and p.G478LfsX23 in samples from eight pedigrees. Both truncating mutations were associated with young onset and very aggressive disease courses, whereas the p.R521H, p.R514G and in particular the p.K510R mutation showed a milder phenotype with disease durations ranging from 3 years to more than 26 years, the longest reported for a patient with a FUS/TLS mutation. Also, in a pair of monozygous twins with the p.K510R mutation, a remarkable similar disease course was observed.

CONCLUSIONS

Mutations in FUS/TLS account for 8.7% (16 of 184) of FALS in Germany. This is a higher prevalence than reported from other countries. Truncating FUS/TLS mutations result in a more severe phenotype than most missense mutations. The wide phenotypic differences have implications for genetic counselling.

Benign symmetric lipomatosis with axonal neuropathy and abnormalities in specific mitochondrial tRNA regions

Benign symmetric lipomatosis, also called Madelung's disease, is characterized by lipomata and fatty infiltrations. Involvement of the nervous system has occasionally been described, mitochondrial dysfunctions have been suggested. We report a 55 year old male suffering from benign symmetric lipomatosis with associated axonal neuropathy and hyperlipoproteinemia. He showed a remarkable phenotype of neuropathy i.e. no sensory disturbance, ubiquitous fasciculations and muscle cramps, furthermore reduced COX activity and abnormalities in specific mitochondrial tRNA regions.

Regulation of the human skeletal muscle chloride channel hClC-1 by protein kinase C

1. The regulation of a recombinant human muscle chloride channel, hClC-1, by protein kinase C (PKC) was investigated in human embryonic kidney (HEK 293) cells. 2. External application of 4beta-phorbol esters (4beta-PMA) reduced the instantaneous whole-cell current amplitude over the entire voltage range tested. This effect was abolished when the cells were intracellularly perfused with a specific protein kinase C inhibitor, chelerythine. Inactive 4alpha-phorbolesters did not affect the chloride currents. We conclude that the effect of 4beta-phorbol esters is mediated by protein kinase C (PKC). 3. Activation of PKC resulted in changes in macroscopic current kinetics. The time course of current deactivation determined in the presence and absence of 4beta-phorbol esters could be fitted with the sum of two exponentials and a constant value. In the presence of phorbol esters, the fast time constants and the minimum value of the fraction of non-deactivating current were increased, whereas the voltage dependence of all fractional current amplitudes remained unchanged. PKC-induced phosphorylation had only small effects on the voltage dependence of the relative open probability and the maximum absolute open probability was unaffected by treatment with 4beta-PMA, as shown by non-stationary noise analysis. 4. The kinetic changes indicate that phosphorylation alters functional properties of active channels. Since the absolute open probability is not reduced, the observed macroscopic current reduction implies alterations of the ion permeation process. 5. Phosphorylation by PKC appears to affect ion transfer and gating processes. It is postulated that the phosphorylation site may be located at the cytoplasmic vestibule face of the pore.

Mechanism of voltage-dependent gating in skeletal muscle chloride channels

Voltage-dependent gating was investigated in a recombinant human skeletal muscle Cl- channel, hCIC-1, heterologously expressed in human embryonic kidney (HEK-293) cells. Gating was found to be mediated by two qualitatively distinct processes. One gating step operates on a microsecond time scale and involves the rapid rearrangement of two identical intramembranous voltage sensors, each consisting of a single titratable residue. The second process occurs on a millisecond time scale and is due to a blocking-unblocking reaction mediated by a cytoplasmic gate that interacts with the ion pore of the channel. These results illustrate a rather simple structural basis for voltage sensing that has evolved in skeletal muscle Cl- channels and provides evidence for the existence of a cytoplasmic gating mechanism in an anion channel analogous to the "ball and chain" mechanism of voltage-gated cation channels.