Gene polymorphisms associated with temperament

Postnatal nighttime light exposure and infant temperament at age 12 months: mediating role of genus Akkermansia

The gut microbiome has been reported to be associated with nighttime light (NTL) exposure and temperament. However, the specific role of infant gut microbiome plays in NTL exposure and temperament is unclear. This study investigated the potential mediating role of infants' gut microbiome in correlations between NTL exposure and temperament. Demographic information, stool samples, and temperament scores were collected from 40 infants. Temperament was evaluated using the Infants Behavior Questionnaire-Revised (IBQ-R). The gut microbiota was analyzed using 16S rRNA sequencing. Cumulative and lagged effects of NTL exposure were calculated based on residential address (NTLpoint) and a concentric 1 km radius buffer zone around the address (NTL1000m), respectively. Mediation models were utilized for assessing the mediating effects of the gut microbiome. The gut microbiome of infants with higher fear scores was characterized by a higher abundance of Akkermansia and Clostridium_sensu_stricto_1 and a lower abundance of Bacteroides. Mediation models indicated Akkermansia played a full mediating role in associations between NTLpoint, NTL1000m and fear in specific time periods. Genus Akkermansia explained 24.46% and 33.50% of associations between fear and cumulative exposure to NTLpoint and NTL1000m, respectively. This study provides evidence for the mediating role of Akkermansia between NTL exposure and fear. However, further experimental is required to elucidate the mechanisms through which the gut microbiome mediates between NTL exposure and temperament in infants.

Identification of Candidate Genes and Pathways Linked to the Temperament Trait in Sheep

Temperament can be defined as the emotional variability among animals of the same species in response to the same stimulus, grouping animals by their reactivity as nervous, intermediate, or calm. Our goal was to identify genomic regions with the temperament phenotype measured by the Isolation Box Test (IBT) by single-step genome-wide association studies (ssGWAS). The database consisted of 4317 animals with temperament records, and 1697 genotyped animals with 38,268 effective Single Nucleotide Polymorphism (SNP) after quality control. We identified three genomic regions that explained the greatest percentage of the genetic variance, resulting in 25 SNP associated with candidate genes on chromosomes 6, 10, and 21. A total of nine candidate genes are reported for the temperament trait, which is: PYGM, SYVN1, CAPN1, FADS1, SYT7, GRID2, GPRIN3, EEF1A1 and FRY, linked to the energetic activity of the organism, synaptic transmission, meat tenderness, and calcium associated activities. This is the first study to identify these genetic variants associated with temperament in sheep, which could be used as molecular markers in future behavioral research.

Changes in the gut microbiome in the first two years of life predicted the temperament in toddlers

BACKGROUND

Temperament has been shown to be associated with the change of gut microbiome. There were no longitudinal studies to explore the role of gut microbiome changes in the development of temperament in toddlers.

METHODS

This study used longitudinal cohort to investigate the associations between changes in gut microbiome and temperament in toddlers in the first two years of life. Linear regression analysis and microbiome multivariate association with linear models were used to investigate the associations between the gut microbiome and toddlers' temperament.

RESULTS

In total, 41 toddlers were analyzed. This study found both Shannon and Chao-1 indices at birth were negatively correlated with the sadness dimension; the higher the Shannon and Chao-1 indices at 6 months, the lower the surgency/extraversion dimension scores; the higher the Shannon and Chao-1 indices at 2 years of ages, the lower the cuddliness dimension scores. After adjusting for covariates, beta diversity at birth was strongly associated with the negative affectivity dimension; beta diversity at 1 year of age was strongly associated with the activity level dimension; and beta diversity at 2 years of age was strongly associated with the discomfort and soothability dimension. Compared to Bifidobacterium cluster, this study also found Bacteroides cluster was associated with lower negative affectivity and its sub-dimensions frustration and sadness scores in toddlers.

LIMITATIONS

Generalizability of the results remains to be determined.

CONCLUSION

Results of this study confirmed the associations between changes in the gut microbiome diversity and composition in the first two years of life and toddlers' temperament.

Relationship between the gut microbiota and temperament in children 1-2 years old in Chinese birth cohort

BACKGROUND

Understanding the relationship between the gut microbiota and temperament can provide new insights for the regulation of behavioral intervention in children, which is still lacking research. This study aimed to examine the relationship between the gut microbiota and temperament in a cohort of children in 1 year and 2 years old.

METHODS

This study included a total of 37 children with completed information, in which 51 samples at age 1 and 41 samples at age 2 were received respectively. We collected birth and demographic information. Parents reported their child's temperament characteristics using the Infant Behavior Questionnaire-revised (IBQ-R) and Early Childhood Behavior Questionnaire (ECBQ). Fecal samples were collected from each child at 1 and 2 years old and sequenced with MiSeq sequencer. Multiple linear regressions and linear mixed effect models were used to analyze the relationship between the temperament and their microbiota composition as well as the diversity and effect of gender or age on this relationship.

RESULTS

At age of year 2, Faecalibacterium was negatively associated with high-intensity pleasure and surgency. Bifidobacterium was negatively correlated with Perceptual sensitivity. Results showed no difference about three domains between year 1 and year 2, while gut microbiota showed diversity difference and genera difference. There was no gender and age difference on the relationship between temperament and the gut microbiota.

CONCLUSIONS

Temperament was associated with the gut microbiota over time. The temperament remained stable and the relationship between the gut microbiota and temperament wasn't associated with age and gender.

Objective Assessment of Temperament in Temperamentally Vulnerable Children: Role in the Studies on Their Stress Levels

Under conditions of suboptimal parental care, children with specific temperamental features have been shown to be especially vulnerable to the effects of stress. Most studies of temperamentally vulnerable children have been conducted using parental questionnaires, which are unfortunately not completely objective. An alternative approach, the use of objective methods for assessing temperament in childhood, can and should be used to study the impact of poor parenting quality on children's stress levels, an important factor in child development. Although studies using such objective methods exist, they are quite rare. A PubMed search identified twelve articles reviewed here. Existing data indicate that, in general, higher basal cortisol and cortisol stress response are associated with "reactive" temperament: shyness, fearfulness, behavioral inhibition, and negative affectivity. Furthermore, child temperament interacts with the quality of parental care to predict cortisol levels in early childhood. Accordingly, in the context of inadequate parental care, temperamentally vulnerable children with "reactive" temperaments are particularly at risk for negative effects of stress. Studies of stress-by-parental-care-interactions are essential for preventing long-term mental problems and problems with physical health that could occur in temperamentally vulnerable children who receive suboptimal parental care.

Single Nucleotide Polymorphisms in Thyroid Hormone Transporter Genes MCT8, MCT10 and Deiodinase DIO2 Contribute to Inter-Individual Variance of Executive Functions and Personality Traits

Thyroid hormones are modulators of cognitive functions, and changes in hormone levels affect intelligence, memory, attention and executive function. Single nucleotide polymorphisms (SNPs) of transporter proteins MCT8, MCT10 and deiodinase 2 (DIO2) influence thyroid metabolism and could therefore contribute to inter-individual variance of cognitive functions. This study investigates the influence of these SNPs using an extensive neuropsychological test battery. 656 healthy participants aged 18-39 years were genotyped for four SNPs: MCT8 (rs5937843 and rs6647476), MCT10 (rs14399) and DIO2 (rs225014) and underwent eleven different neuropsychological tests as well as four personality questionnaires. Test results were compared between homo- and heterozygous carriers and for the X-linked MCT8 additionally between men and women. Personality questionnaires revealed that Risk Seeking was reduced in homozygous T carriers and highest in homozygous C carriers of the DIO2 SNP and that both polymorphisms of MCT8 had an additive effect on Physical Aggression in men. Neuropsychological testing indicated that MCT10 affects nonverbal reasoning abilities, DIO2 influences working memory and verbal fluency and MCT8 influences attention, alertness and planning. This pilot study suggests an influence of polymorphisms in thyroid hormone transporter genes and deiodinase on cognitive domains and personality traits.

Genetic control of temperament traits across species: association of autism spectrum disorder risk genes with cattle temperament

Background

Temperament traits are of high importance across species. In humans, temperament or personality traits correlate with psychological traits and psychiatric disorders. In cattle, they impact animal welfare, product quality and human safety, and are therefore of direct commercial importance. We hypothesized that genetic factors that contribute to variation in temperament among individuals within a species will be shared between humans and cattle. Using imputed whole-genome sequence data from 9223 beef cattle from three cohorts, a series of genome-wide association studies was undertaken on cattle flight time, a temperament phenotype measured as the time taken for an animal to cover a short-fixed distance after release from an enclosure. We also investigated the association of cattle temperament with polymorphisms in bovine orthologs of risk genes for neuroticism, schizophrenia, autism spectrum disorders (ASD), and developmental delay disorders in humans.

Results

Variants with the strongest associations were located in the bovine orthologous region that is involved in several behavioural and cognitive disorders in humans. These variants were also partially validated in independent cattle cohorts. Genes in these regions (BARHL2, NDN, SNRPN, MAGEL2, ABCA12, KIFAP3, TOPAZ1, FZD3, UBE3A, and GABRA5) were enriched for the GO term neuron migration and were differentially expressed in brain and pituitary tissues in humans. Moreover, variants within 100 kb of ASD susceptibility genes were associated with cattle temperament and explained 6.5% of the total additive genetic variance in the largest cattle cohort. The ASD genes with the most significant associations were GABRB3 and CUL3. Using the same 100 kb window, a weak association was found with polymorphisms in schizophrenia risk genes and no association with polymorphisms in neuroticism and developmental delay disorders risk genes.

Conclusions

Our analysis showed that genes identified in a meta-analysis of cattle temperament contribute to neuron development functions and are differentially expressed in human brain tissues. Furthermore, some ASD susceptibility genes are associated with cattle temperament. These findings provide evidence that genetic control of temperament might be shared between humans and cattle and highlight the potential for future analyses to leverage results between species.

Recent insights into the evolution of quantitative traits in non-human primates

The past few years of genetic research on primate quantitative trait variation have been notable in the diversity of phenotypes explored, ranging from classic skeletal measurements to behavior, through to levels of gene expression, and with observations from both captive and wild populations. These studies demonstrate the importance of captive pedigreed breeding colonies, populations that can be matched to their wild counterparts to enable comparison of genetic architectures. Non-human primate genotype:phenotype maps are essential for placing human variation within an evolutionary framework as well as for gaining insight to human biology. While the demographic history of most primates has been fairly stable since the Late Pleistocene, humans experienced a dramatic population expansion that increased the number of rare, mildly deleterious mutations. These rare genetic variants complicate the genotype:phenotype association because they account for a disproportionate amount of the genetic variance and are harder to detect. The similar physiologies of our closest living relatives may prove to be key for overcoming the hurdles posed by humans' peculiar demographic explosion.