No genetic association between attention-deficit/hyperactivity disorder (ADHD) and Parkinson's disease in nine ADHD candidate SNPs
ADHD-ATTENTION DEFICIT AND HYPERACTIVITY DISORDERS
Authors: Geissler, Julia M.; Romanos, Marcel; Gerlach, Manfred; Berg, Daniela; Schulte, Claudia
Abstract
Attention-deficit/hyperactivity disorder (ADHD) and Parkinson's disease (PD) involve pathological changes in brain structures such as the basal ganglia, which are essential for the control of motor and cognitive behavior and impulsivity. The cause of ADHD and PD remains unknown, but there is increasing evidence that both seem to result from a complicated interplay of genetic and environmental factors affecting numerous cellular processes and brain regions. To explore the possibility of common genetic pathways within the respective pathophysiologies, nine ADHD candidate single nucleotide polymorphisms (SNPs) in seven genes were tested for association with PD in 5333 cases and 12,019 healthy controls: one variant, respectively, in the genes coding for synaptosomal-associated protein 25 k (SNAP25), the dopamine (DA) transporter (SLC6A3; DAT1), DA receptor D4 (DRD4), serotonin receptor 1B (HTR1B), tryptophan hydroxylase 2 (TPH2), the norepinephrine transporter SLC6A2 and three SNPs in cadherin 13 (CDH13). Information was extracted from a recent meta-analysis of five genome-wide association studies, in which 7,689,524 SNPs in European samples were successfully imputed. No significant association was observed after correction for multiple testing. Therefore, it is reasonable to conclude that candidate variants implicated in the pathogenesis of ADHD do not play a substantial role in PD.
Investigation of Leukocyte Telomere Length and Genetic Variants in Chromosome 5p15.33 as Prognostic Markers in Lung Cancer
CANCER EPIDEMIOLOGY BIOMARKERS & PREVENTION
Authors: Kachuri, Linda; Helby, Jens; Bojesen, Stig Egil; Christiani, David C.; Su, Li; Wu, Xifeng; Tardon, Adonina; Fernandez-Tardon, Guillermo; Field, John K.; Davies, Michael P.; Chen, Chu; Goodman, Gary E.; Shepherd, Frances A.; Leighl, Natasha B.; Tsao, Ming S.; Brhane, Yonathan; Brown, M. Catherine; Boyd, Kevin; Shepshelovich, Daniel; Sun, Lei; Amos, Christopher I.; Liu, Geoffrey; Hung, Rayjean J.
Abstract
Background: Lung cancer remains the leading cause of cancer mortality with relatively few prognostic biomarkers. We investigated associations with overall survival for telomere length (TL) and genetic variation in chromosome 5p15.33, an established telomere maintenance locus. Methods: Leukocyte TL was measured after diagnosis in 807 patients with non-small cell lung cancer (NSCLC) from the Princess Margaret Cancer Center in Toronto and assessed prospectively in 767 NSCLC cases from the Copenhagen City Heart Study and the Copenhagen General Population Study. Associations with all-cause mortality were tested for 723 variants in 5p15.33, genotyped in 4,672 NSCLC cases. Results: Short telomeres (<= 10th percentile) were associated with poor prognosis for adenocarcinoma in both populations: TL measured 6 months after diagnosis [HR = 1.65; 95% confidence intervals (CI), 1.04-2.64] and for those diagnosed within 5 years after blood sampling (HR = 2.42; 95% CI, 1.37-4.28). Short TL was associated with mortality in never smokers with NSCLC (HR = 10.29; 95% CI, 1.86-56.86) and adenocarcinoma (HR = 11.31; 95% CI, 1.96-65.24). Analyses in 5p15.33 identified statistically significant prognostic associations for rs56266421-G in LPCAT1 (HR = 1.86; 95% CI, 1.38-2.52; P = 4.5 x 10(-5)) in stage I-IIIA NSCLC, and for the SLC6A3 gene with OS in females with NSCLC (P = 1.6 x 10(-3)). Conclusions: Our findings support the potential clinical utility of TL, particularly for adenocarcinoma patients, while associations in chromosome 5p15.33 warrant further exploration. Impact: This is the largest lung cancer study of leukocyte TL and OS, and the first to examine the impact of the timing of TL measurement. Our findings suggest that extremely short telomeres are indicative of poor prognosis in NSCLC.