Tobacco exposure and sleep disturbance in 498 208 UK Biobank participants.

Background: The prevalence of sleep disturbance is high and increasing. The study investigated whether active, former and passive smoking were associated with sleep disturbance. Methods: This cross-sectional study used data from the UK Biobank: a cohort study of 502 655 participants, of whom 498 208 provided self-reported data on smoking and sleep characteristics. Multivariable multinomial and logistic regression models were used to examine the associations between smoking and sleep disturbance. Results: Long-sleep duration (>9 h) was more common among current smokers [odds ratio (OR): 1.47; 95% confidence interval (CI): 1.17-1.85; probability value (P) = 0.001] than never smokers, especially heavy (>20/day) smokers (OR: 2.85; 95% CI: 1.66-4.89; P < 0.001). Former heavy (>20/day) smokers were also more likely to report short (<6 h) sleep duration (OR: 1.41; 95% CI: 1.25-1.60; P < 0.001), long-sleep duration (OR: 1.99; 95% CI: 1.47-2.71; P < 0.001) and sleeplessness (OR: 1.47; 95% CI: 1.38-1.57; P < 0.001) than never smokers. Among never smokers, those who lived with more than one smoker had higher odds of long-sleep duration than those not cohabitating with a smoker (OR: 2.71; 95% CI: 1.26-5.82; P = 0.011). Conclusions: Active and passive exposure to high levels of tobacco smoke are associated with sleep disturbance. Existing global tobacco control interventions need to be enforced.

Dietary fat and total energy intake modifies the association of genetic profile risk score on obesity: evidence from 48 170 UK Biobank participants.

BACKGROUND: Obesity is a multifactorial condition influenced by both genetics and lifestyle. The aim of this study was to investigate whether the association between a validated genetic profile risk score for obesity (GPRS-obesity) and body mass index (BMI) or waist circumference (WC) was modified by macronutrient intake in a large general population study. METHODS: This study included cross-sectional data from 48 170 white European adults, aged 37-73 years, participating in the UK Biobank. Interactions between GPRS-obesity and macronutrient intake (including total energy, protein, fat, carbohydrate and dietary fibre intake) and its effects on BMI and WC were investigated. RESULTS: The 93-single-nucleotide polymorphism (SNP) GPRS was associated with a higher BMI (ß: 0.57 kg m-2 per s.d. increase in GPRS (95% confidence interval: 0.53-0.60); P=1.9 × 10-183) independent of major confounding factors. There was a significant interaction between GPRS and total fat intake (P(interaction)=0.007). Among high-fat-intake individuals, BMI was higher by 0.60 (0.52, 0.67) kg m-2 per s.d. increase in GPRS-obesity; the change in BMI with GPRS was lower among low-fat-intake individuals (ß: 0.50 (0.44, 0.57) kg m-2). Significant interactions with similar patterns were observed for saturated fat intake (high ß: 0.66 (0.59, 0.73) versus low ß: 0.49 (0.42, 0.55) kg m-2, P(interaction)=2 × 10-4) and for total energy intake (high ß: 0.58 (0.51, 0.64) versus low ß: 0.49 (0.42, 0.56) kg m-2, P(interaction)=0.019), but not for protein intake, carbohydrate intake and fibre intake (P(interaction) >0.05). The findings were broadly similar using WC as the outcome. CONCLUSIONS: These data suggest that the benefits of reducing the intake of fats and total energy intake may be more important in individuals with high genetic risk for obesity.

Genome-wide analysis of over 106 000 individuals identifies 9 neuroticism-associated loci.

Neuroticism is a personality trait of fundamental importance for psychological well-being and public health. It is strongly associated with major depressive disorder (MDD) and several other psychiatric conditions. Although neuroticism is heritable, attempts to identify the alleles involved in previous studies have been limited by relatively small sample sizes. Here we report a combined meta-analysis of genome-wide association study (GWAS) of neuroticism that includes 91 370 participants from the UK Biobank cohort, 6659 participants from the Generation Scotland: Scottish Family Health Study (GS:SFHS) and 8687 participants from a QIMR (Queensland Institute of Medical Research) Berghofer Medical Research Institute (QIMR) cohort. All participants were assessed using the same neuroticism instrument, the Eysenck Personality Questionnaire-Revised (EPQ-R-S) Short Form's Neuroticism scale. We found a single-nucleotide polymorphism-based heritability estimate for neuroticism of ∼15% (s.e.=0.7%). Meta-analysis identified nine novel loci associated with neuroticism. The strongest evidence for association was at a locus on chromosome 8 (P=1.5 × 10(-15)) spanning 4 Mb and containing at least 36 genes. Other associated loci included interesting candidate genes on chromosome 1 (GRIK3 (glutamate receptor ionotropic kainate 3)), chromosome 4 (KLHL2 (Kelch-like protein 2)), chromosome 17 (CRHR1 (corticotropin-releasing hormone receptor 1) and MAPT (microtubule-associated protein Tau)) and on chromosome 18 (CELF4 (CUGBP elav-like family member 4)). We found no evidence for genetic differences in the common allelic architecture of neuroticism by sex. By comparing our findings with those of the Psychiatric Genetics Consortia, we identified a strong genetic correlation between neuroticism and MDD and a less strong but significant genetic correlation with schizophrenia, although not with bipolar disorder. Polygenic risk scores derived from the primary UK Biobank sample captured ∼1% of the variance in neuroticism in the GS:SFHS and QIMR samples, although most of the genome-wide significant alleles identified within a UK Biobank-only GWAS of neuroticism were not independently replicated within these cohorts. The identification of nine novel neuroticism-associated loci will drive forward future work on the neurobiology of neuroticism and related phenotypes.

DNA yield and quality of saliva samples and suitability for large-scale epidemiological studies in children.

OBJECTIVE: To evaluate two saliva collection methods for DNA yield and quality as applied to a large, integrated, multicentre, European project involving the collection of biological material from children. DESIGN: Cross-sectional multicentre comparative study in young children. METHODS: Saliva samples were collected from 14,019 children aged 2-9 years from eight European countries participating in the IDEFICS (Identification and prevention of dietary- and lifestyle-induced health effects in children and infants) study. This involved either the collection of 2 ml of saliva from children who were able to spit, or using a sponge to collect whole saliva and buccal mucosal cells from the inside of the mouth of younger children unable to spit. Samples were assembled centrally in each participating centre and subsequently despatched for DNA extraction and biobanking to the University of Glasgow. A subgroup of 4678 samples (∼33% of sampled individuals) were chosen for DNA extraction before genotyping. RESULTS: The whole-saliva collection method resulted in a higher DNA yield than the sponge collection method (mean±s.d.; saliva: 20.95±2.35 µg, sponge: 9.13±2.25 µg; P<0.001). DNA quality as measured by A (260)/A (280) was similar for the two collection methods. A minimum genotype calling success rate of 95% showed that both methods provide good-quality DNA for genotyping using TaqMan allelic discrimination assays. CONCLUSIONS: Our results showed higher DNA yield from the whole-saliva collection method compared with the assisted sponge collection. However, both collection methods provided DNA of sufficient quantity and quality for large-scale genetic epidemiological studies.

Synaptic plasticity deficits in an experimental model of rett syndrome: long-term potentiation saturation and its pharmacological reversal.

Rett syndrome (RTT), a disorder caused almost exclusively by mutations in the X-linked gene, MECP2, has a phenotype thought to be primarily of neurological origin. Disruption of Mecp2 in mice results in a prominent RTT-like phenotype. One of the consequences of MeCP2 absence in the brain is altered functional and structural plasticity. We aimed to characterize synaptic effects related to plasticity in the hippocampus further and establish whether plasticity defects are amenable to pharmacological reversal. Using male mice in which Mecp2 expression was prevented by a stop cassette, we assessed synaptic plasticity in area CA1 at different phenotypic stages, scoring the mice weekly for overt RTT-like signs. Strongly symptomatic Mecp2(stop/y) mice displayed reduced long-term potentiation (LTP, 40.2±1.6% of wild-type), post-tetanic potentiation (PTP, 45±18.8% of wild-type) and paired-pulse facilitation (PPF, 78±0.1% of wild type) (all P<0.05), the impairment increasing with symptom severity score. These plasticity impairments were absent in presymptomatic mice. Repeated high frequency stimulation revealed pronounced LTP saturation in symptomatic Mecp2(stop/y) mice, suggesting an LTP 'ceiling' effect. Bath application of the weak NMDA receptor blocker memantine (1 µM) resulted in partial restoration of a short-term plasticity component. These data support that idea that progressive functional synaptic impairment is a key feature in the RTT brain and demonstrate the potential for the pharmacological restoration of plasticity function.

Familial Ménière's disease: clinical and genetic aspects.

BACKGROUND AND PURPOSE: Ménière's disease is not uncommon, with an incidence in Caucasians of about one in 2000. The incidence peaks in the fifth decade. Cases are usually isolated or sporadic, but in perhaps five per cent other family members are affected. We report here the clinical and genetic characteristics of a comprehensive set of familial Ménière's disease cases from the UK. METHODS: Forty-six affected families were studied. All cases were diagnosed using the American Academy of Otolaryngology-Head and Neck Surgery committee on hearing and equilibrium 1995, or more stringent, criteria. OUTCOMES AND RESULTS: Autosomal dominant inheritance with reduced penetrance was the most likely mode of inheritance overall. Apparent genetic anticipation was observed, but may also be a result of ascertainment bias given the collection strategy. There was also a slight tendency for cases to result from maternal transmission within the families in this set. The family pedigrees are presented, and the authors have also set up a website at which all the pedigrees may be viewed in greater detail.

Developmental changes in adiposity in toddlers and preschoolers in the GENESIS study and associations with the ACE I/D polymorphism.

OBJECTIVES: To investigate the relationship between the angiotensin I-converting enzyme 1 (ACE) I/D polymorphism and adiposity-related phenotypes in a large cohort of toddlers and preschoolers. METHODS: Body composition measurements and DNA samples were obtained from 2102 Greek children aged 1-6 years, as part of a large-scale epidemiological study (GENESIS). All children were genotyped for the ACE I/D polymorphism and gender- and age-stratified statistical analyses were performed. RESULTS: In girls aged 4-6 years, the D-allele was associated with higher measurements of body mass index (BMI) (P=0.018), waist (P=0.001) and upper arm (P=0.013) circumferences, genotype accounting for 2.5, 4 and 3% of the phenotypic variance, respectively. In boys, the D-allele showed strong associations with lower BMI (P=0.001) at the age of 1-2 years that explained 17% of the phenotypic variance and with larger suprailiac skinfold (P=0.008) at 3-4 years old that explained 2% of the variance. No other significant associations between the ACE I/D polymorphism and adiposity-related phenotypes were found. In girls, the age at which significant associations were revealed coincided with the age at which BMI was observed to increase after its developmental nadir, but this feature of the association was not observed in boys. CONCLUSIONS: The ACE I/D polymorphism is associated with developmental and physiological changes in adiposity-related traits during early childhood in a gender- and age-specific manner.