A Genetic Population Isolate in The Netherlands Showing Extensive Haplotype Sharing and Long Regions of Homozygosity.

Genetic isolated populations have features that may facilitate genetic analyses and can be leveraged to improve power of mapping genes to complex traits. Our aim was to test the extent to which a population with a former history of geographic isolation and religious endogamy, and currently with one of the highest fertility rates in The Netherlands, shows signs of genetic isolation. For this purpose, genome-wide genotype data was collected of 72 unrelated individuals from this population as well as in a sample of 104 random control subjects from The Netherlands.

Linkage analysis in a Dutch population isolate shows no major gene for left-handedness or atypical language lateralization.

Cerebral dominance of language function and hand preference are suggested to be heritable traits with possible shared genetic background. However, joined genetic studies of these traits have never been conducted. We performed a genetic linkage study in 37 multigenerational human pedigrees of both sexes (consisting of 355 subjects) enriched with left-handedness in which we also measured language lateralization.

On the relationship between degree of hand-preference and degree of language lateralization.

Language lateralization and hand-preference show inter-individual variation in the degree of lateralization to the left- or right, but their relation is not fully understood. Disentangling this relation could aid elucidating the mechanisms underlying these traits. The relation between degree of language lateralization and degree of hand-preference was investigated in extended pedigrees with multi-generational left-handedness (n=310).

Risk score for predicting adolescent mental health problems among children using parental report only: the TRAILS study.

Objective: To construct a risk score for adolescent mental health problems among children, using parental data only and without potentially stigmatizing mental health items.

Methods: We prospectively derived a prediction model for mental health problems at age 16 using data from parent report on 1676 children aged 11 from the general population. Mental health problems were considered present in the top 15% scores on the combined Achenbach ratings.

BDNF Val66Met homozygosity does not influence plasma BDNF levels in healthy human subjects.

A putative pathway by which the BDNF Val66Met polymorphism (rs6265) leads to aberrant phenotypes is its influence on plasma BDNF. Research into the impact of rs6265 on plasma BDNF has given rise to conflicting results. Moreover, most such studies have compared Met-carriers with Val-homozygous subjects.

Familial clustering of schizophrenia, bipolar disorder, and major depressive disorder.

Purpose: To investigate familial clustering of schizophrenia, bipolar disorder, and major depressive disorder.

Methods: Combining data from a psychiatric case registry and Statistics Netherlands provided information on 4,673 affected probands and 18,692 matched population controls.

Results: Probands with schizophrenia had relative risks (RRs) for having a sibling with schizophrenia of 3.

The association of the alpha-5 subunit of the nicotinic acetylcholine receptor gene and the brain-derived neurotrophic factor gene with different aspects of smoking behavior.

Recent studies show that different aspects of smoking behavior are associated with the α-5 subunit of the nicotinic acetylcholine receptor (CHRNA5) gene and the gene coding for brain-derived neurotrophic factor (BDNF). This raises the question whether the amount of cigarettes smoked per day has a different genetic background than smoking initiation and what other smoking phenotypes may be relevant. The aim of this study was to replicate these associations in a large population-based sample.

Paternal age and psychiatric disorders: findings from a Dutch population registry.

Background: We measured the association between paternal age and schizophrenia (SCZ), autism spectrum disorders (ASD), major depressive disorder (MDD), and bipolar disorder (BPD) in the Dutch population.

Methods: In total, 14231 patients and 56924 matched controls were collected and analyzed for an association with paternal age by logistic regression.

Results: ASD is significantly associated with increased paternal age: Older fathers >40 years of age have a 3.

Finding suitable phenotypes for genetic studies of schizophrenia: heritability and segregation analysis.

Background: Schizophrenia is a highly heritable and complex disorder. Multiple genes are likely to be involved, complicating genetic research into the etiology of this disorder. Intermediate phenotypes or endophenotypes may facilitate genetic research if they display a simpler mode of transmission than schizophrenia itself, i.

No evidence for a preferential transmission of the methylenetetrahydrofolate reductase 677T allele in families with schizophrenia offspring.

The methylenetetrahydrofolate reductase (MTHFR) 677C > T polymorphism has been associated with an increased risk of schizophrenia in various case-control studies. However, case-control studies are sensitive to population stratification, which is not an issue in family-based studies. We conducted a family-based study comprising 120 families with a schizophrenic family member to explore the association between the parental MTHFR 677C > T polymorphism and schizophrenia risk in offspring.

Perceptual switching, eye movements, and the bus paradox.

According to a widely cited finding by Ellis and Stark (1978 Perception 7 575-581), the duration of eye fixations is longer at the instant of perceptual reversal of an ambiguous figure than before or after the reversal. However, long fixations are more likely to include samples of an independent random event than are short fixations. This sampling bias would produce the pattern of results also when no correlation exists between fixation duration and perceptual reversals.