Population differences in associations of serotonin transporter promoter polymorphism (5HTTLPR) di- and triallelic genotypes with blood pressure and hypertension prevalence

Genetic determinants of blood pressure and heart rate identified through ENU-induced mutagenesis with automated meiotic mapping

We used N-ethyl-N-nitrosurea-induced germline mutagenesis combined with automated meiotic mapping to identify specific systolic blood pressure (SBP) and heart rate (HR) determinant loci. We analyzed 43,627 third-generation (G3) mice from 841 pedigrees to assess the effects of 45,378 variant alleles within 15,760 genes, in both heterozygous and homozygous states. We comprehensively tested 23% of all protein-encoding autosomal genes and found 87 SBP and 144 HR (with 7 affecting both) candidates exhibiting detectable hypomorphic characteristics. Unexpectedly, only 18 of the 87 SBP genes were previously known, while 26 of the 144 genes linked to HR were previously identified. Furthermore, we confirmed the influence of two genes on SBP regulation and three genes on HR control through reverse genetics. This underscores the importance of our research in uncovering genes associated with these critical cardiovascular risk factors and illustrate the effectiveness of germline mutagenesis for defining key determinants of polygenic phenotypes that must be studied in an intact organism.

Alexithymia is associated with increased all-cause mortality risk in men, but not in women: A 10-year follow-up study

OBJECTIVE

Alexithymia is associated with various mental as well as physical disorders. Some evidence also suggested high alexithymia to increase mortality risk, but these results are few and based on specific sample compositions. We aimed to investigate the impact of alexithymia on mortality risk in a large population based cohort. In addition, we sought to elucidate the effects of the subfactors of alexithymia and sex differences.

METHODS

In a sample of N = 1380 individuals from the Study of Health in Pomerania (SHIP), we investigated the hazard-ratio (HR) of alexithymia as obtained by the Toronto Alexithymia Scale-20 (TAS-20) on all-cause mortality over an average observation time of 10 years. Sex-by-TAS-20-interactions as well as sex-stratified analyses were performed.

RESULTS

Alexithymia was significantly associated with enhanced mortality risk (HR = 1.033; 95%-CI = 1.008-1.058); p = 0.009). While sex-by-TAS-20 interactions remained insignificant, sex-stratified analyses showed that this effect was only significant in men (HR = 1.050; 95%-CI = 1.022-1.079; p ≤ 0.001), but not in women (HR: 1.008; 95%-CI = 0.960-1.057; p = 0.76). The effect was validated for the "difficulties identifying feelings" (DIF) and "difficulties describing feelings" (DDF) subfactors of the TAS-20.

CONCLUSION

Our study supports and extents previous findings by indicating that mortality risk enhancing effects of alexithymia are specific to male subjects and validated for the DIF and DDF facets. Socioeconomic, clinical and metabolic factors were associated with this relationship. Finding that the impact of alexithymia remains stable in the fully adjusted models suggests that yet unidentified additional factors must be considered.

Hypertension in a multi-ethnic Asian population of Singapore

The prevalence of hypertension varies by country and region, but it remains a leading yet modifiable risk factor of cardiovascular disease. There are many factors that contribute to the burden of hypertension in Asia, a region with diverse ethnicity. It has been shown that sociodemographic variability is related to ethnic differences, thereby emphasizing the importance of hypertension screening and educating at-risk or vulnerable groups. In this review, we describe the ethnic differences in genetic variants, dietary choice, and lifestyle habits, as well as its association with sociodemographic differences, hypertension awareness, and treatment control.

Association of 5-HTTLPR/rs25531 with depressive symptoms in patients with coronary heart disease: A prospective study

BACKGROUND

5-HTTLPR/rs25531 is suspected to be involved in the pathogenesis of both coronary heart disease (CHD)¹ and depression. We aimed to investigate the role of 5-HTTLPR/rs25531 in the development of depressive symptoms among CHD patients in a longitudinal design.

METHODS

N = 265 participants with CHD diagnosis were included while hospitalized in a department of cardiology and genotyped for the 5-HTTLPR/rs25531. Depressive symptoms were measured using the Patient Health Questionnaire (PHQ-9)⁷ at baseline and after 6 and 12 months. Binary logistic regression models were used to analyze the association of 5-HTTLPR/rs25531 with the prevalence of depressive symptoms at each time point as well as with the incidence and persistence of depressive symptoms at follow-up.

RESULTS

"L_AL_A" genotype was associated with a higher prevalence of depressive symptoms 12 months after study inclusion. "L_AL_A" genotype was associated with a higher incidence of depressive symptoms 6 and 12 months after study inclusion. There was no association of 5-HTTLPR/rs25531 with the persistence of depressive symptoms.

LIMITATIONS

Inclusion criteria did not demand a particular cardiac event at baseline, which aggravated the interpretation of the time-specific results. The majority of the participants was of male gender which could cause bias. The present study only vaguely differentiated between ethnical groups which might cause bias regarding nationality-dependent allele distributions.

CONCLUSION

The present study suggests a time-dependent association of the "L_AL_A" genotype with depressive symptoms in CHD patients. 5-HTTLPR/rs25531 might be an important marker to detect risk groups for later onset depressive symptoms among CHD patients.

Timing of suicide in people with epilepsy: A population-based study from 18 states of the United States, 2003-2014

Suicide timing varies across several psychiatric disorders, which may share common underlying pathophysiological mechanisms with epilepsy. We investigated suicide timing in people with epilepsy. Using cross-sectional, population-based U.S. National Violent Death Reporting System data from 2003 through 2014 in 18 States, we identified 1310 suicides with epilepsy and 102,582 suicides without epilepsy among those 10 years and older. We compared patterns of suicide mortality ratios between those with and without epilepsy by month of year, week of month, day of week, time of day, and overall by age, sex, and race/ethnicity. As the suicide patterns seen among persons without epilepsy, suicides in persons with epilepsy occurred significantly more often during the morning, afternoon, and evening hours than at night in all subgroups except females. Compared to Sundays, suicides in persons with epilepsy were only significantly increased on Mondays and Tuesdays in those aged ≥45 years and only on Mondays in men. This pattern differs from persons without epilepsy whose suicides significantly increased on Mondays and significantly decreased on Saturdays in nearly all study subgroups. Suicides in persons with epilepsy did not exhibit the timing patterns of persons without epilepsy by week of month (significant decreases from the third to fifth weeks compared to the first week among those aged ≥45 years, males, and Non-Hispanic whites) and month of year (significant increases from January to November peaking from June to September compared to December in all study groups). Compared to the general population or people without epilepsy, previous and current studies suggest that in people with epilepsy, suicide timing differs from and suicide rates significantly exceed those in people without epilepsy. Preventing suicide in people with epilepsy should focus not only on the peak times of occurrence but also across all time periods.

The serotonin transporter gene variants modulate acute stress-induced hippocampus and dorsomedial prefrontal cortex activity during memory retrieval

The short (s) allele of a polymorphism in the promoter region of the serotonin transporter gene (5-HTTLPR) is related to reduced serotonin transporter efficiency and an increased vulnerability to stress and mental disorders. In the present study, we investigated how 5-HTTLPR impacts on memory retrieval under stress and related neural activity by reanalyzing a small genetic neuroimaging data set. Twenty-seven healthy male volunteers participated in both the Trier Social Stress Test (TSST) and a respective control procedure and then their brain activity was measured with functional MRI (fMRI) while they performed an emotional-face-recognition task. Sixteen participants were carriers of the short allele (ss/sl carriers) and 11 were homozygous for the long allele (ll carriers). Genotype groups were compared with respect to stress-related physiological changes, memory performance, and brain activity. No significant genotype-dependent effects on memory performance or cortisol levels were found. The ss/sl carriers showed significantly higher systolic and diastolic blood pressure than the ll carriers, independent of stress. The ss/sl carriers reported stronger stress-induced nervous mood than the ll carriers. Our fMRI data revealed that the ss/sl carriers showed significantly weaker left hippocampus activation and stronger dorsomedial prefrontal cortex (dmPFC) deactivation when retrieving memories under stress as compared with the ll carriers. Subsequent analyses revealed that the distinct hippocampal activation pattern in both genotypes was associated with stress-induced cortisol elevation, while the distinct dmPFC activation pattern in both genotypes was associated with stress-induced changes in reaction times. Our results thus add new evidence that serotonin signaling modulates neural activity in the hippocampus and dmPFC during memory retrieval under acute psychosocial stress.

Adaptive developmental plasticity in rhesus macaques: the serotonin transporter gene interacts with maternal care to affect juvenile social behaviour

Research has increasingly highlighted the role that developmental plasticity-the ability of a particular genotype to produce variable phenotypes in response to different early environments-plays as an adaptive mechanism. One of the most widely studied genetic contributors to developmental plasticity in humans and rhesus macaques is a serotonin transporter gene-linked polymorphic region (5-HTTLPR), which determines transcriptional efficiency of the serotonin transporter gene in vitro and modifies the availability of synaptic serotonin in these species. A majority of studies to date have shown that carriers of a loss-of-function variant of the 5-HTTLPR, the short (s) allele, develop a stress-reactive phenotype in response to adverse early environments compared with long (l) allele homozygotes, leading to the prevalent conceptualization of the s-allele as a vulnerability allele. However, this framework fails to address the independent evolution of these loss-of-function mutations in both humans and macaques as well as the high population prevalence of s-alleles in both species. Here we show in free-ranging rhesus macaques that s-allele carriers benefit more from supportive early social environments than l-allele homozygotes, such that s-allele carriers which receive higher levels of maternal protection during infancy demonstrate greater social competence later in life. These findings provide, to our knowledge, the first empirical support for the assertion that the s-allele grants high undirected biological sensitivity to context in primates and suggest a mechanism through which the 5-HTTLPR s-allele is maintained in primate populations.

Suicide Timing in 18 States of the United States from 2003-2014

We investigated suicide timing over different time periods by age, sex and race/ethnicity. A total of 122,107 suicide deaths were identified from the population-based U.S. National Violent Death Reporting System in 18 U.S. states from 2003 through 2014. Suicides significantly increased (p < .05) from March to peak in September before falling, the first week of the month, and early in the week. Suicides also significantly increased (p < .05) in the morning, mainly peaking during the afternoon, although suicides in adolescents peaked in the evening and in those 65-years and older peaked in the morning. Comprehensive prevention efforts should focus on those at overall increased suicide risk and at peaks of high suicide frequency, especially among those vulnerable subgroups.