Lack of evidence for an association between the V393A variant of COQ2 and amyotrophic lateral sclerosis in a Han Chinese population

Absence of association of the Ala58Val (rs17571) CTSD gene variant with Parkinson's disease or amyotrophic lateral sclerosis in a Han Chinese population

Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS) and Alzheimer's disease (AD) are neurodegenerative diseases that may share genetic risk factors. The exon variant Aal58Val (rs17571) in CTSD was recently associated with AD, leading us to examine whether it also affects risk of ALS and PD. The rs17571 variant was genotyped using the ligase detection reaction in 569 Han Chinese patients with PD, 301 patients with ALS, and healthy controls age- and gender-matched to each patient group. The frequencies of genotypes and alleles were similar between each disease group and its respective control group. Similar results were obtained when patients were stratified by gender, age at disease onset or type of symptoms at disease onset. These results suggest that the CTSD rs17571 variant may not be associated with risk of ALS or PD in Han Chinese.

Decreased Coenzyme Q10 Levels in Multiple System Atrophy Cerebellum

In familial and sporadic multiple system atrophy (MSA) patients, deficiency of coenzyme Q10 (CoQ10) has been associated with mutations in COQ2, which encodes the second enzyme in the CoQ10 biosynthetic pathway. Cerebellar ataxia is the most common presentation of CoQ10 deficiency, suggesting that the cerebellum might be selectively vulnerable to low levels of CoQ10 To investigate whether CoQ10 deficiency represents a common feature in the brains of MSA patients independent of the presence of COQ2 mutations, we studied CoQ10 levels in postmortem brains of 12 MSA, 9 Parkinson disease (PD), 9 essential tremor (ET) patients, and 12 controls. We also assessed mitochondrial respiratory chain enzyme activities, oxidative stress, mitochondrial mass, and levels of enzymes involved in CoQ biosynthesis. Our studies revealed CoQ10 deficiency in MSA cerebellum, which was associated with impaired CoQ biosynthesis and increased oxidative stress in the absence of COQ2 mutations. The levels of CoQ10 in the cerebella of ET and PD patients were comparable or higher than in controls. These findings suggest that CoQ10 deficiency may contribute to the pathogenesis of MSA. Because no disease modifying therapies are currently available, increasing CoQ10 levels by supplementation or upregulation of its biosynthesis may represent a novel treatment strategy for MSA patients.

Association Analysis of COQ2 Variant in Dementia and Essential Tremor

Objective. COQ2 mutations have been reported in Japanese multiple system atrophy (MSA) patients. We examined the role of COQ2 in patients with dementia and essential tremor (ET), two common neurodegenerative conditions. Materials & Methods. A total of 2064 subjects, including 560 patients with dementia, 466 patients with ET, and 1038 healthy controls, were included. Genotyping for the COQ2 V393A (T>C) was carried out. Odds ratio (OR) adjusted by age and gender, together with 95% confidence interval (CI), was reported by means of logistic regression. Results. The frequency of the polymorphic variant V393A heterozygous (T/C) was 2.7% in dementia, 1.1% in ET, and 2.5% in controls (OR = 0.70, 95% confidence interval is 0.29-1.72 for dementia, and OR = 0.47, 95% confidence interval is 0.17-1.31, p = 0.1217 for ET). There was no significant association between V393A variant with dementia and ET. Conclusion. There was no significant association between V393A variant with dementia and ET. COQ2 gene is unlikely to play a significant role in patients with dementia or ET in our population.