Lack of association between the LRRK2 A419V variant and Asian Parkinson's disease

<p><b>INTRODUCTION</b>The G2385R and R1628P LRRK2 gene variants have been associated with an increased risk of Parkinson's disease (PD) in the Asian population. Recently, a new LRRK2 gene variant, A419V, was reported to be a third risk variant for PD in Asian patients. Our objective was to investigate this finding in our cohort of Asian subjects.</p><p><b>MATERIALS AND METHODS</b>Eight hundred and twenty-eight subjects (404 PD patients, and 424 age and gender-matched control subjects without neurological disorders) were recruited. Genotyping was done by Taqman® allelic discrimination assay on an Applied Biosystems 7500 Fast Real-Time PCR machine.</p><p><b>RESULTS</b>The heterozygous A419V genotype was found in only 1 patient with PD, compared to 3 in the control group (0.4% vs 1.3%), giving an odds ratio of 0.35 (95% confidence interval (CI), 0.01 to 3.79; P = 0.624).</p><p><b>CONCLUSION</b>A419V is not an important LRRK2 risk variant in our Asian cohort of patients with PD. Our data are further supported by a literature review which showed that 4 out of 6 published studies reported a negative association of this variant in PD.</p>

Diffusion-weighted magnetic resonance imaging in a case of osmotic demyelination syndrome with fatal outcome

Hyponatraemia with rapid correction of serum sodium may cause an osmotic demyelination syndrome (ODS) with damage to pontine and/or extrapontine areas of the brain. The prognosis of ODS can range from complete recovery to death; at present, our ability to predict clinical outcome is very limited. We describe here a patient with ODS and increased signal intensity in the striatum on diffusion-weighted MRI, with corresponding low apparent diffusion coeffi cient values (indicating restricted water diffusion). This case provides a further example of the typical MRI appearance of extrapontine ODS and suggests the potential value of diffusion-weighted MRI in predicting prognosis in ODS.