Genome-wide analysis of rare copy number variations reveals PARK2 as a candidate gene for attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD) is a common, highly heritable neurodevelopmental disorder. Genetic loci have not yet been identified by genome-wide association studies. Rare copy number variations (CNVs), such as chromosomal deletions or duplications, have been implicated in ADHD and other neurodevelopmental disorders. To identify rare (frequency 1%) CNVs that increase the risk of ADHD, we performed a whole-genome CNV analysis based on 489 young ADHD patients and 1285 adult population-based controls and identified one significantly associated CNV region. In tests for a global burden of large (>500 kb) rare CNVs, we observed a nonsignificant (P=0.271) 1.126-fold enriched rate of subjects carrying at least one such CNV in the group of ADHD cases. Locus-specific tests of association were used to assess if there were more rare CNVs in cases compared with controls. Detected CNVs, which were significantly enriched in the ADHD group, were validated by quantitative (q)PCR. Findings were replicated in an independent sample of 386 young patients with ADHD and 781 young population-based healthy controls. We identified rare CNVs within the parkinson protein 2 gene (PARK2) with a significantly higher prevalence in ADHD patients than in controls (P=2.8 × 10(-4) after empirical correction for genome-wide testing). In total, the PARK2 locus (chr 6: 162 659 756-162 767 019) harboured three deletions and nine duplications in the ADHD patients and two deletions and two duplications in the controls. By qPCR analysis, we validated 11 of the 12 CNVs in ADHD patients (P=1.2 × 10(-3) after empirical correction for genome-wide testing). In the replication sample, CNVs at the PARK2 locus were found in four additional ADHD patients and one additional control (P=4.3 × 10(-2)). Our results suggest that copy number variants at the PARK2 locus contribute to the genetic susceptibility of ADHD. Mutations and CNVs in PARK2 are known to be associated with Parkinson disease.Molecular Psychiatry advance online publication, 20 November 2012; doi:10.1038/mp.2012.161.

Genetic variations in IL28B and allergic disease in children

Environmental changes affecting the relationship between the developing immune system and microbial exposure have been implicated in the epidemic rise of allergic disease in developed countries. While early developmental differences in T cell function are well-recognised, there is now emerging evidence that this is related to developmental differences in innate immune function. In this study we sought to examine if differences associated with innate immunity contribute to the altered immune programming recognised in allergic children. Here, we describe for the first time, the association of carriage of the T allele of the tagging single nucleotide polymorphism rs12979860 3 kb upstream of IL28B, encoding the potent innate immune modulator type III interferon lambda (IFN-λ3), and allergy in children (p = 0.004; OR 4.56). Strikingly, the association between rs12979860 genotype and allergic disease is enhanced in girls. Furthermore, carriage of the T allele at rs12979860 correlates with differences in the pro-inflammatory profile during the first five years of life suggesting this contributes to the key differences in subsequent innate immune development in children who develop allergic disease. In the context of rising rates of disease, these immunologic differences already present at birth imply very early interaction between genetic predisposition and prenatal environmental influences.

Genetic variations in bile acid homeostasis are not overrepresented in alcoholic cirrhosis compared to patients with heavy alcohol abuse and absent liver disease

Increased serum bile salt levels have been associated to a single-nucleotide polymorphism in the bile salt export pump (BSEP; ABCB11) in several acquired cholestatic liver diseases but there is little evidence in alcoholic liver disease (ALD). Furthermore, a crosstalk between vitamin D and bile acid synthesis has recently been discovered. Whether this crosstalk has an influence on the course of ALD is unclear to date. Our aim was to analyse the role of genetic polymorphisms in BSEP and the vitamin D receptor gene (NR1I1) on the emergence of cirrhosis in patients with ALD. Therefore, 511 alcoholic patients (131 with cirrhosis and 380 without cirrhosis) underwent ABCB11 genotyping (rs2287622). Of these, 321 (131 with cirrhosis and 190 without cirrhosis) were also tested for NR1I1 polymorphisms (bat-haplotype: BsmI rs1544410, ApaI rs7975232 and TaqI rs731236). Frequencies of ABCB11 and NR1I1 genotypes and haplotypes were compared between alcoholic patients with and without cirrhosis and correlated to serum bile salt, bilirubin and aspartate aminotransferase levels in those with cirrhosis. Frequencies of ABCB11 and NR1I1 genotypes and haplotypes did not differ between the two subgroups and no significant association between genotypes/haplotypes and liver function tests could be determined for neither polymorphism. We conclude that ABCB11 and NR1I1 polymorphisms are obviously not associated with development of cirrhosis in patients with ALD.

Sequence variations in the von Hippel-Lindau tumor suppressor gene in patients with intracranial aneurysms

The rupture of intracranial aneurysms leads to subarachnoid hemorrhage, which is often associated with poor outcome. Preventive treatment of unruptured intracranial aneurysms is possible and recommended. However, the lack of candidate genes precludes identifying patients at risk by genetic analyses. We observed intracranial aneurysms in 2 patients with von Hippel-Lindau (VHL) disease and the known disease-causing mutation c.292T > C (p.Tyr98His) in the VHL tumor suppressor gene. This study investigates whether the VHL gene is a possible candidate gene for aneurysm formation.

Seasonal variations of ventricular arrhythmia clusters in defibrillator recipients

BACKGROUND: Clustering ventricular arrhythmias are the consequence of acute ventricular electrical instability and represent a challenge in the management of the growing number of patients with an implantable cardioverter-defibrillator (ICD). Triggering factors can rarely be identified. OBJECTIVES: Several studies have revealed seasonal variations in the frequency of cardiovascular events and life-threatening arrhythmias, and we sought to establish whether seasonal factors may exacerbate ventricular electrical instability leading to arrhythmia clusters and electrical storm. METHODS: Two hundred and fourteen consecutive defibrillator recipients were followed-up during 3.3 +/- 2.2 years. Arrhythmia cluster was defined as the occurrence of three or more arrhythmic events triggering appropriate defibrillator therapies within 2 weeks. Time intervals between two clusters were calculated for each month and each season, and were compared using Kruskal-Wallis test and Wilcoxon-Mann-Whitney test with Bonferroni adjustment. RESULTS: During a follow-up of 698 patient years, 98 arrhythmia clusters were observed in 51 patients; clustering ventricular arrhythmias were associated with temporal variables; they occurred more frequently in the winter and spring months than during the summer and fall. Accordingly, the time intervals between two clusters were significantly shorter during winter and spring (median and 95% CI): winter 16 (5-19), spring 11.5 (7-25), summer 34.5 (15-55), fall 50.5 (19-65), P = 0.0041. CONCLUSION: There are important seasonal variations in the incidence of arrhythmia clusters in ICD recipients. Whether these variations are related to environmental factors, change in physical activity, or psychological factors requires further study.