Identification of FUS p.R377W in essential tremor

BACKGROUND AND PURPOSE

Exome sequencing analysis has recently identified a nonsense mutation in fused in sarcoma (FUS) segregating with essential tremor (ET) within a large French-Canadian family. Further characterization of FUS resulted in the identification of additional mutations in ET patients; however, their pathogenicity still remains to be confirmed. The role of FUS in an independent cohort of ET patients from Canada was evaluated.

METHODS

The entire coding sequence of FUS in 217 patients diagnosed with ET was analyzed and two missense variants in 219 healthy controls were genotyped by Sanger sequencing.

RESULTS

Sequencing of FUS identified a previously reported non-pathogenic mutation p.G174_G175del in one ET patient and two healthy controls, and a novel p.R377W in one patient with family history of disease. This mutation is highly conserved and strongly predicted to be damaging by in silico analysis.

CONCLUSION

This study has identified a novel FUS p.R377W substitution in ET patients. Additional genotyping studies in a large number of ET patients and controls are necessary to conclusively define its pathogenicity.

Course in Parkinson disease subtypes: A 39-year clinicopathologic study

BACKGROUND

Individual variations in the course of Lewy body Parkinson disease (PD) are well known. Patients have been classified into different clinical subtypes to identify differences in the course among the subgroups. Several studies indicate that the outcome is more favorable in tremor dominant (TD) cases but others report no difference. A majority of progression studies are based on cross-sectional single point data or short-term clinical observations. The lack of longitudinally followed autopsy-confirmed PD cohort remains a major weakness in the literature. Biochemical studies of brain indicate most pronounced abnormalities in akinetic/rigid (AR) and the least in TD cases. We postulate that PD course in these subtypes is concordant with the biochemical findings.

OBJECTIVE

To compare the course in TD, mixed (MX), and AR subtypes of PD.

METHODS

Longitudinal clinical follow-up and autopsy studies were performed on 166 patients with PD over 39 years (1968-2006). Patients were classified into TD, AR, and MX based on the entire clinical course. Only the pathologically confirmed PD cases were included.

RESULTS

Sixty-six percent of cases had MX, 26% AR, and 8% TD profile. The age at onset was younger (p < 0.001) and progression to Hoehn & Yahr stage 4 was slower (p = 0.016) in the TD cases. Dementia was most common in AR (p = 0.039) and the least common in TD. In general, the course was most favorable in TD, followed by MX and AR subgroups.

CONCLUSION

The three subtypes of Parkinson disease have different courses which are concordant with the differences in brain biochemical abnormalities.

Parkinsonism, Lrrk2 G2019S, and tau neuropathology

Lrrk2 G2019S is predominantly associated with alpha-synuclein-immunopositive Lewy body pathology. We have identified Family SK where Lrrk2 G2019S segregates with slowly progressive parkinsonism and the affected proband has tau-immunopositive neurofibrillary tangle pathology. Thus alpha-synucleinopathy and tauopathy, the predominant pathologies associated with parkinsonism, may be alternate outcomes of the same underlying genetic cause. Intriguingly, we observe no evidence of a direct interaction between either the tau or alpha-synuclein protein with Lrrk2.

A randomized, double-blind placebo-controlled trial of iron in restless legs syndrome

BACKGROUND

Previous open-label trials have shown iron to be efficacious in the treatment of restless legs syndrome. We performed a randomized, double-blind, placebo-controlled trial of iron sulfate.

METHODS

Twenty-eight patients were randomized to receive either ferrous sulfate 325 mg b.i.d. or placebo for 12 weeks. The primary outcome measure was the dichotomous variable of improvement or no improvement in average quality of sleep as recorded by a visual analog scale nightly over a 2-week period, comparing a pretreatment 2-week baseline to weeks 13-14. Secondary outcome measures included a comparison of the quality of sleep as measured by a visual analog scale, effect of restless legs syndrome on life as a whole as measured by a different visual analog scale, and the percentage of nights patients were symptomatic.

RESULTS

No significant differences were noted between iron and placebo groups for both primary and secondary outcome measures. Responders taking iron did have a significant increase in their iron saturation compared to nonresponders taking iron.

CONCLUSIONS

Iron sulfate does not appear to be an effective empiric treatment for restless legs syndrome.