Assessment of the Genetic Characteristics of a Generation Born during a Long-Term Socioeconomic Crisis

BACKGROUND

A socioeconomic crisis in Russia lasted from 1991 to 1998 and was accompanied by a sharp drop in the birth rate. The main factor that influenced the refusal to have children during this period is thought to be prolonged social stress.

METHODS

comparing frequencies of common gene variants associated with stress-induced diseases among generations born before, after, and during this crisis may show which genes may be preferred under the pressure of natural selection during periods of increased social stress in urban populations.

RESULTS

In the "crisis" group, a statistically significant difference from the other two groups was found in rs6557168 frequency (p = 0.001); rs4522666 was not in the Hardy-Weinberg equilibrium in this group, although its frequency did not show a significant difference from the other groups (p = 0.118). Frequencies of VNTRs in SLC6A3 and MAOA as well as common variants rs17689918 in CRHR1, rs1360780 in FKBP5, rs53576 in OXTR, rs12720071 and rs806377 in CNR1, rs4311 in ACE, rs1800497 in ANKK1, and rs7412 and rs429358 in APOE did not differ among the groups.

CONCLUSIONS

a generation born during a period of prolonged destructive events may differ from the rest of the gene pool of the population in some variants associated with personality traits or stress-related disorders.

Athletic performance, sports experience, and exercise addiction: an association study on ANKK1 gene polymorphism rs1800497

Introduction

Exercise addiction is a phenomenon being able to affecting the athletic performance. The gene, ANKK1 and the polymorphism NM_178510.2:c.2137G > A (rs1800497) has been linked to the exercise addiction. However, further studies on diverse populations and sport branches are needed to totally explore the possible association of this polymorphism with the athletic performance. Thus, the present study aims to decipher any possible relations of the rs1800497 polymorphism with the athletic performance/personal best (PB) and sport experience of elite athletes.

Methods

Sixty volunteer elite athletes (31 sprint/power and 29 endurance) and 20 control/sedentary participated in the study. The polymorphism was genotyped using whole exome sequencing approach and PB were determined according to the International Association of Athletics Federations (IAAF) score.

Results

Our results underlined that there were not any significance differences for both allele and genotype frequencies between the groups in terms of athletic performance, although the frequency of allele G was higher (p > 0.05). Nevertheless, sport experience significantly associated with the rs1800496 polymorphism (p < 0.05).

Discussion

In conclusion, genotype G/G could be inferred to be linked to the higher sport experience and athletic performance. Still, further studies with higher number of participants are needed to conclude the association of this polymorphism with athletic parameters.

Effect of ANKK1 Polymorphisms on Serum Valproic Acid Concentration in Chinese Han Adult Patients in the Early Postoperative Period

INTRODUCTION

This study aimed to investigate the relationship between gene polymorphisms and clinical factors with the concentrations of valproic acid (VPA) in adult patients who underwent neurosurgery in China.

METHODS

A total of 531 serum concentration samples at steady state were collected from 313 patients to develop a population pharmacokinetic (PPK) model. Data analysis was performed using nonlinear mixed effects modeling. Covariates included demographic parameters, biological characteristics, and genetic polymorphism. Bootstrap evaluation showed that the final model was stable. Sensitive analysis was performed to verify the relationship between gene polymorphisms and concentrations of VPA. Linear regression was used to analyze the relationship between VPA concentration, ANKK1, and daily dosage.

RESULTS

In the recruited patients, 17 of 25 single-nucleotide polymorphism distributions were consistent with the Hardy-Weinberg equilibrium. A one-compartment model with first-order absorption and elimination was developed for VPA injections. VPA clearance was significantly influenced by three variables: sex (17.41% higher in male than female patients), body weight, and the ANKK1 gene. Typical values for the elimination clearance and the volume of central compartment were 0.614 L/min and 23.5 L, respectively. The model evaluation indicated the stable and precise performance of the final model. After sensitive analysis using Kruskal-Wallis and Mann-Whitney U tests, we found that patients with AA alleles had higher VPA concentrations than those with GG and AG alleles. Linear regression models showed that gene polymorphisms of ANKK1 had little effects on VPA concentration.

CONCLUSION

A PPK model of VPA in Chinese Han patients was successfully established; this can be helpful for model-informed precision-dosing approaches in clinical patient care, and for exploring the mechanism of VPA-induced weight gain.

Association Between DRD2 and DRD4 Polymorphisms and Eating Disorders in an Italian Population

Anorexia nervosa (AN), bulimia nervosa (BN), and binge eating disorder (BED) are the three most common eating disorders (EDs). Their etiopathogenesis is multifactorial where both the environmental and genetic factors contribute to the disease outcome and severity. Several polymorphisms in genes involved in the dopaminergic pathways seem to be relevant in the susceptibility to EDs, but their role has not been fully elucidated yet. In this study, we have analyzed the association between selected common polymorphisms in the DRD2 and DRD4 genes in a large cohort of Italian patients affected by AN (n = 332), BN (n = 122), and BED (n = 132) compared to healthy controls (CTRs) (n = 172). Allelic and genotypic frequencies have been also correlated with the main psychopathological and clinical comorbidities often observed in patients. Our results showed significant associations of the DRD2-rs6277 single nucleotide polymorphism (SNP) with AN and BN, of the DRD4-rs936461 SNP with BN and BED and of DRD4 120-bp tandem repeat (TR) polymorphism (SS plus LS genotypes) with BED susceptibility. Moreover, genotyping of DRD4 48-bp variable number TR (VNTR) identified the presence of ≥7R alleles as risk factors to develop each type of EDs. The study also showed that ED subjects with a history of drugs abuse were characterized by a significantly higher frequency of the DRD4 rs1800955 TT genotype and DRD4 120-bp TR short-allele. Our findings suggest that specific combinations of variants in the DRD2 and DRD4 genes are predisposing factors not only for EDs but also for some psychopathological features often coupled specifically to AN, BN, and BED. Further functional research studies are needed to better clarify the complex role of these proteins and to develop novel therapeutic compounds based on dopamine modulation.

ANKK1 and TH gene variants in combination with paternal maltreatment increase susceptibility to both cognitive and attentive impulsivity

Recent scientific findings suggest that dopamine exerts a central role on impulsivity, as well as that aversive life experiences may promote the high levels of impulsivity that often underlie violent behavior. To deepen our understanding of the complex gene by environment interplay on impulsive behavior, we genotyped six dopaminergic allelic variants (ANKK1-rs1800497, TH-rs6356, DRD4-rs1800955, DRD4-exonIII-VNTR, SLC6A3-VNTR and COMT-rs4680) in 655 US White male inmates convicted for violent crimes, whose impulsivity was assessed by BIS-11 (Barratt Impulsiveness Scale). Furthermore, in a subsample of 216 inmates from the whole group, we also explored the potential interplay between the genotyped dopaminergic variants and parental maltreatment measured by MOPS (Measure of Parental Style) in promoting impulsivity. We found a significant interaction among paternal MOPS scores, ANKK1-rs1800497-T allele and TH-rs6356-A allele, which increased the variance of BIS-11 cognitive/attentive scores explained by paternal maltreatment from 1.8 up to 20.5%. No direct association between any of the individual genetic variants and impulsivity was observed. Our data suggest that paternal maltreatment increases the risk of attentive/cognitive impulsivity and that this risk is higher in carriers of specific dopaminergic alleles that potentiate the dopaminergic neurotransmission. These findings add further evidence to the mutual role that genetics and early environmental factors exert in modulating human behavior and highlight the importance of childhood care interventions.

GABAA subunit single nucleotide polymorphisms show sex-specific association to alcohol consumption and mental distress in a Norwegian population-based sample

Little is known about genetic influences on the relationship between alcohol consumption and mental distress in the general population, where the majority report consumption and distress far below diagnostic thresholds. This study investigated single nucleotide polymorphisms (SNPs) from candidate gene studies on alcohol use disorder and depressive disorders, for association with alcohol consumption and with mental distress in a population-based sample from the Cohort of Norway (n = 1978, 49% women). The relationship between alcohol consumption and mental distress was further examined for genotype modification. There was a positive correlation between mental distress and alcohol consumption in men, as well as an association between SNPs and mental distress in men (GABRG1, GABRA2, DRD2, ANKK1, MTHFR) and women (CHRM2, MTHFR) and between SNPs and alcohol consumption in women (GABRA2, MTHFR). No modification by SNP genotype was found on the relationship between alcohol consumption and mental distress. The association between mental distress and GABRG1 in men remained significant after correcting for multiple comparisons. The results indicate that alcohol consumption and mental distress are associated in the general population even at levels below clinical thresholds and point to SNPs in genes related to GABAergic signalling for level of mental distress in men.

Genotypes of ANKK1 and DRD2 genes and risk of metabolic syndrome and its components: A cross-sectional study on Iranian women

We aimed to investigate the association between polymorphism of DRD2/ANKK1 gene with MetS and its components. Women (n = 531, aged 19-50 years) from the North-west of Iran were included by cluster sampling method. Polymorphisms of ANKK1 and DRD2 genes were defined in the study population. D/D (OR: 3.16; 95%CI: 1.31-7.60) and I/D (OR: 1.76; 95%CI: 1.12-2.78) genotypes of DRD2 (rs1799732) increased risk of MetS compared to I/I genotype. The D/D genotype of DRD2 (rs1799732) increased odds of hypertriglyceridemia in the study population. T/T (OR: 6.72; 95%CI: 1.99-22.71) and C/T (OR: 4.42; 95%CI: 2.79-7.01) genotypes of ANKK1 (rs1800497) increased risk of MetS compared to C/C genotype. Also, C/T genotype increased the odds of HTN, high FBS, high TG and low HDL-C levels compared to C/C genotype. These polymorphisms can affect the MetS components via their relation to the signaling of dopaminergic pathways and eating behaviors.

Analysis of Selected Variants of DRD2 and ANKK1 Genes in Combat Athletes

The level of physical activity is conditioned by many different factors, including, among others, the personality traits of a person. Important is the fact that personality traits are a moderately heritable factor and on the basis of the analysis of several genes, various lifetime outcomes can be predicted. One of the most important pathways influencing personality traits is connected to the dopaminergic system; hence, we decided to analyze the DRD2 PROM. rs1799732, DRD2 rs1076560, DRD2 Tag1D rs1800498, DRD2 Ex8 rs6276, DRD2Tag1B rs1079597 and ANKK1 Tag1A rs180049. The research group included 258 male athletes (mean age = 26.02; SD = 8.30), whereas the control group was 284 healthy male volunteers matched for age (mean age = 22.89; SD = 4.78), both of Caucasian origin and without history of substance dependency or psychosis. Genomic DNA was extracted from venous blood using standard procedures. Genotyping was conducted with the real-time PCR method. Differences in the frequency of the DRD2Tag1B rs1079597 gene polymorphism were found between people practicing combat sports and the control group, and the DRD2 PROM. rs1799732, DRD2 rs1076560, DRD2 Tag1D rs1800498, DRD2 Ex8 rs6276, DRD2Tag1B rs1079597 and ANKK1 Tag1A rs1800497 genotypes and allele frequencies in the studied sample did not differ between the analyzed groups. Hence, we considered these polymorphic places as an interesting area for the further search for unambiguous associations between personality traits and attitude towards physical effort.

Association of Candidate Single Nucleotide Polymorphisms Related to Candidate Genes in Patients With Schizophrenia

Introduction:

Schizophrenia is a chronic heterogenic neurodevelopment disorder. Many genes interfere in the development of SCZ. All four genes, NrCAM, PRODH, ANK3, and ANKK1, which were evaluated in this study, were previously reported to be associated with Schizophrenia. The NrCAM contributes to creating cognitive deficiencies through the CAM’s signaling pathway. PRODH plays a vital role in creating SCZ negative symptoms through the signaling pathway of glutamatergic and NMDA receptors. ANK3 affects ion channel and molecular adhesion in Ranvier and initial segments of axons, leading to mental retardation, sleep disorder, and SCZ. ANKK1 encodes a protein kinase and was reported to be associated with alcohol addiction, Attention Deficit Hyperactivity Disorder (ADHD), and SCZ.

Methods:

The subjects were selected from Schizophrenic patients referring to the Psychiatric Ward of Imam-Hussein Hospital and Schizophrenic Patients Support Institution (AHEBBA). 95 (30 Schizoaffective patients, 57 Paranoid patients, and 8 disorganized) patients were recruited as the subjects in the present case-control association study. 120 healthy subjects were recruited from the Tehran Medical Genetics Laboratory staff and a group of students from the Islamic Azad University of Science and Research in Tehran. The genotypes were determined with molecular genotyping techniques of PCR-RFLP, ARMS-PCR, and Cycle sequencing. Results were analyzed by the Chi-Square test using SPSS V. 24 and R, SNP STATE Package to investigate significant differences between cases and controls.

Results:

The incidence of schizophrenia was 68% and 32% among men and women, respectively. The evaluation of the allelic association between schizophrenia and all the candidate SNPs showed a significant association between NrCAM’s SNP rs10235968 and SCZ (P=0.001). Haplotype T, T, C in rs10235968, rs6967368, rs3763463, respectively, within the NrCAM gene, showed significant association with schizophrenia disorder (P=0.0001).

Conclusion:

No association was found between other candidate SNPs and SCZ among the subjects.

Associations of the ANKK1 and DRD2 gene polymorphisms with overweight, obesity and hedonic hunger among women from the Northwest of Iran

BACKGROUND

Pleasure from palatable foods can stimulate hedonic eating and, therefore, might be a major culprit for obesity. Dopamine receptor polymorphisms, especially variants in the genes regulating the D2 receptor, including ANKK1 and DRD2, are the prime candidates for assessing the individual differences in hedonic eating. This study was carried out to investigate the possible associations of the T (rs1800497) and Del (rs1799732) alleles with body mass index (BMI) and hedonic hunger among Iranian Azeri women.

METHODS

A total of 372 healthy overweight/obese subjects (BMI ≥ 25 kg/m²) and 159 normal weight individuals (BMI 18.5-24.9 kg/m²) were genotyped for the polymorphisms of ANNK1 and DRD2 genes using PCR-RFLP. BMI and hedonic hunger were also evaluated.

RESULTS

Three hundred and sixty-three (68.36%), 152 (28.63%), and 16 (3.01%) of the participants had CC, CT, and TT genotypes for ANNK1 gene, respectively. Of 515 samples genotyped for DRD2 gene, 315 (60.51%), 173 (33.59%), and 27 (5.24%) had Ins/Ins, Ins/Del, and Del/Del genotypes, respectively. The genotype and genotype frequencies were significantly different between the groups (p = 0.04). Significant differences were observed between the T+ genotype (TT + TC) and the T- genotype (CC) regarding the BMI and hedonic hunger scores (p < 0.05). In addition, Del+ group (Del/Del + Ins/Del) had higher BMI and hedonic hunger scores compared to Del- group (Ins/Ins) (p < 0.05).

CONCLUSIONS

Our findings showed that the frequencies of T and Del alleles were greater in the overweight/obese individuals. Also, the polymorphism of ANKK1 (rs1800497) and polymorphism of the DRD2 gene (rs1799732) showed significant associations with BMI and hedonic hunger.

LEVEL OF EVIDENCE

Level III, case-control study.

Suicidal ideation and aggression in childhood, genetic variation and young adult depression

BACKGROUND

Suicidal thoughts and behaviors have been studied in association with a variety of risk factors. The aim of the present study was to determine if levels of child/adolescent aggression and/or variation in candidate genes previously associated with suicidal behaviors in adults would influence the presence of suicidal ideation in childhood/adolescence, and to determine if ideation was associated with young adult depression.

METHODS

A longitudinal study of children, adolescents and young adults who were at high or low risk for alcohol and other substance use disorders by familial background were assessed. The Child Behavior Checklist (CBCL) aggression scale scores with derived subtypes (physical and relational) and genetic variation (ANKK1, DRD2, COMT, SLC6A4, HTR2C) were used as predictors of the presence and onset of suicidal ideation in childhood using survival analysis. Structural equation models (SEM) were fit to determine the relative importance of the predictors controlling for background variables.

RESULTS

CBCL aggression was significantly associated with child/adolescent suicidal ideation. One SNP in the ANKK1 gene (rs1800497), one in the HTR2C gene (rs6318), and two haplotypes, AAAC in the ANKK1-DRD2 complex and the CCC haplotype of the HTR2C gene, were significantly associated with the presence and onset of child/adolescent suicidal ideation. Follow up in young adulthood showed a significant relationship between suicidal ideation in childhood/adolescence and young adult depression.

CONCLUSIONS

Genetic variation and presence of elevated aggression scores from the childhood CBCL are significant predictors of childhood suicidal ideation. Suicidal ideation in childhood and being female are predictors of young adult depression.

Ankyrin Repeat and Kinase Domain Containing 1 Gene, and Addiction Vulnerability

The TaqIA single nucleotide variant (SNV) has been tested for association with addictions in a huge number of studies. TaqIA is located in the ankyrin repeat and kinase domain containing 1 gene (ANKK1) that codes for a receptor interacting protein kinase. ANKK1 maps on the NTAD cluster along with the dopamine receptor D2 (DRD2), the tetratricopeptide repeat domain 12 (TTC12) and the neural cell adhesion molecule 1 (NCAM1) genes. The four genes have been associated with addictions, although TTC12 and ANKK1 showed the strongest associations. In silico and in vitro studies revealed that ANKK1 is functionally related to the dopaminergic system, in particular with DRD2. In antisocial alcoholism, epistasis between ANKK1 TaqIA and DRD2 C957T SNVs has been described. This clinical finding has been supported by the study of ANKK1 expression in peripheral blood mononuclear cells of alcoholic patients and controls. Regarding the ANKK1 protein, there is direct evidence of its location in adult and developing central nervous system. Together, these findings of the ANKK1 gene and its protein suggest that the TaqIA SNV is a marker of brain differences, both in structure and in dopaminergic function, that increase individual risk to addiction development.

Association between DRD2 and ANKK1 polymorphisms with the deficit syndrome in schizophrenia

BACKGROUND

The clinical course of schizophrenia varies among patients and is difficult to predict. Some patient populations present persistent negative symptoms, referred to as the deficit syndrome. Compared to relatives of non-deficit schizophrenia patients, family members of this patient population are at an increased risk of developing schizophrenia. Therefore, the aim of this study was to search for genetic underpinnings of the deficit syndrome in schizophrenia.

METHODS

Three SNPs, i.e., rs1799732 and rs6276 located within DRD2, and rs1800497 within ANKK1, were identified in the DNA samples of 198 schizophrenia probands, including 103 patients with deficit (DS) and 95 patients with non-deficit schizophrenia (NDS). Results: No significant differences concerning any of the analyzed polymorphisms were found between DS and NDS patients. However, significant links were observed between family history of schizophrenia and the deficit syndrome, G/G genotype and rs6276 G allele. In a separate analysis, we identified significant differences in frequencies of rs6276 G allele between DS and NDS patients with family history of schizophrenia. No significant associations were found between DRD2 and ANKK1 SNPs and the age of onset or schizophrenia symptom severity.

CONCLUSIONS

The results of our preliminary study fail to provide evidence of associations between DRD2 and ANKK1 polymorphisms with the deficit syndrome or schizophrenia symptom severity, but suggest potential links between rs6276 in DRD2 and the deficit syndrome in patients with hereditary susceptibility to schizophrenia. However, further studies are necessary to confirm this observation.

Complete sequence of the ANKK1 gene in Mexican-Mestizo individuals with obesity, with or without binge eating disorder

BACKGROUND

The aim of this study was to investigate if Mexican-Mestizo individuals with obesity, with or without binge eating disorder (BED), exhibited mutations or other type of genetic variants in the sequence of ANKK1.

SUBJECTS AND METHODS

Fifty unrelated individuals (21-53 years of age) with obesity, of Mexican-Mestizo ethnic origin were included; 25 of them had BED and 25 presented obesity without BED. The diagnosis of BED was based on criteria proposed in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). Besides, we also analyzed 100 individuals with normal body mass index. DNA from blood leukocytes was amplified by the polymerase chain reaction and all exons of ANKK1 were sequenced.

RESULTS

After ANKK1 sequencing we did not find any mutations; however, we observed various polymorphisms. One polymorphism, rs4938013 in exon 2 showed an association with obesity, whilst rs1800497 (also known as Taq1A) in exon 8, showed an association with BED (P = 0.020). Remarkable, for this study, the number of individuals for both polymorphisms for and additive model was sufficient to derive strong statistical power (80%, with a P < 0.05).

CONCLUSIONS

To our knowledge, this constitutes the first report where the complete sequences of ANKK1 has been analyzed in individuals with obesity, with or without BED. No mutations were found; however, one polymorphism was associated with obesity, with or without BED, and another one was associated with BED.

The Moderating Effect of the Ankyrin Repeat and Kinase Domain Containing One Gene on the Association of Family Environment with Longitudinal Executive Function following Traumatic Brain Injury in Early Childhood: A Preliminary Study

This study examined whether the ankyrin repeat and kinase domain containing 1 gene (ANKK1) C/T single-nucleotide polymorphism (SNP) rs1800497 moderated the association of family environment with long-term executive function (EF) following traumatic injury in early childhood. Caregivers of children with traumatic brain injury (TBI) and children with orthopedic injury completed the Behavior Rating Inventory of Executive Function (BRIEF) at post-injury visits. DNA was collected to identify the rs1800497 genotype in the ANKK1 gene. General linear models examined gene-environment interactions as moderators of the effects of TBI on EF at two times post-injury (12 months and 7 years). At 12 months post-injury, analyses revealed a significant three-way interaction of genotype with level of permissive parenting and injury type. Post hoc analyses showed genetic effects were more pronounced for children with TBI from more positive family environments, such that children with TBI who were carriers of the risk allele (T-allele) had significantly poorer EF compared with non-carriers only when they were from more advantaged environments. At 7 years post-injury, analyses revealed a significant two-way interaction of genotype with level of authoritarian parenting. Post hoc analyses found that carriers of the risk allele had significantly poorer EF compared with non-carriers only when they were from more advantaged environments. These results suggest a gene-environment interaction involving the ANKK1 gene as a predictor of EF in a pediatric injury population. The findings highlight the importance of considering environmental influences in future genetic studies on recovery following TBI and other traumatic injuries in childhood.

DNA methylation of ANKK1 and response to aripiprazole in patients with acute schizophrenia: A preliminary study

Epigenetic modification including DNA methylation may affect pathophysiology and the response to antipsychotic drugs in patients with schizophrenia. The objective of the present study was to investigate the effect of the DNA methylation of ANKK1 (ankyrin repeat and kinase domain containing 1) on the response to aripiprazole and plasma levels of monoamine metabolites in antipsychotic-free acute schizophrenia patients. The subjects were 34 Japanese patients with schizophrenia who had been treated with aripiprazole for 6 weeks. Comprehensive DNA methylation of ANKK1 was determined using a next-generation sequencer. DNA methylation levels at CpG site 387 of ANKK1 were higher in responders to treatment with aripiprazole and correlated with the changes in Positive and Negative Syndrome Scale scores, although the associations did not remain significant after Bonferroni correction. In responders, methylation at all CpG sites was significantly correlated with plasma levels of homovanillic acid (r = 0.587, p = 0.035) and 3-methoxy-4hydroxyphenylglycol (r = 0.684, p = 0.010) at baseline. Despite our non-significant results after multiple correction, our preliminary findings suggest that methylation levels at CpG site 387 of ANKK1 may be associated with treatment response to aripiprazole. Furthermore, methylation of ANKK1 may affect dopaminergic neural transmission in the treatment of schizophrenia, and may influence treatment response. Caution is needed in interpreting these findings because of the small sample size, and further studies are needed to confirm and expand our preliminary results.

Influence of the DRD2/ANKK1 Taq1A polymorphism on caudate volume in older adults without dementia

Dopaminergic neuromodulation is critically important for brain and cognitive integrity. The DRD2/ANKK1 Taq1A polymorphism is associated with striatal dopamine (DA) D2 receptor availability. Some previous studies have found that the A allele of the Taq1A polymorphism influences brain structure, but the results are inconsistent, likely due to population heterogeneity and small sample sizes. We investigated the genetic effect on caudate volume in a large sample of older adults without dementia. Results show that A-allele carriers have smaller caudate volume compared to non-carriers in relatively older adults (n = 167; Mage = 77.8 years), whereas the genotype did not influence caudate volume in a younger age group (n = 220; Mage = 62.8 years). Cognitive performance was not significantly affected by the DRD2 gene. Our findings extend previous observations by showing magnified genetic effects on brain volume in old age, and provide evidence for a link between a DA-related genetic polymorphism and grey matter volume in a brain region within the nigrostriatal dopaminergic pathway.

The Addiction-Related Protein ANKK1 is Differentially Expressed During the Cell Cycle in Neural Precursors

TaqIA is a polymorphism associated with addictions and dopamine-related traits. It is located in the ankyrin repeat and kinase domain containing 1 gene (ANKK1) nearby the gene for the dopamine D2 receptor (D2R). Since ANKK1 function is unknown, TaqIA-associated traits have been explained only by differences in D2R. Here we report ANKK1 studies in mouse and human brain using quantitative real-time PCR, Western blot, immunohistochemistry, and flow cytometry. ANKK1 mRNA and protein isoforms vary along neurodevelopment in the human and mouse brain. In mouse adult brain ANKK1 is located in astrocytes, nuclei of postmitotic neurons and neural precursors from neurogenic niches. In both embryos and adults, nuclei of neural precursors show significant variation of ANKK1 intensity. We demonstrate a correlation between ANKK1 and the cell cycle. Cell synchronization experiments showed a significant increment of ANKK1-kinase in mitotic cells while ANKK1-kinase overexpression affects G1 and M phase that were found to be modulated by ANKK1 alleles and apomorphine treatment. Furthermore, during embryonic neurogenesis ANKK1 was expressed in slow-dividing neuroblasts and rapidly dividing precursors which are mitotic cells. These results suggest a role of ANKK1 during the cell cycle in neural precursors thus providing biological support to brain structure involvement in the TaqIA-associated phenotypes.

DRD2: Bridging the Genome and Ingestive Behavior

Recent work highlights the importance of genetic variants that influence brain structure and function in conferring risk for polygenic obesity. The neurotransmitter dopamine (DA) has a pivotal role in energy balance by integrating metabolic signals with circuits supporting cognitive, perceptual, and appetitive functions that guide feeding. It has also been established that diet and obesity alter DA signaling, leading to compulsive-like feeding and neurocognitive impairments. This raises the possibility that genetic variants that influence DA signaling and adaptation confer risk for overeating and cognitive decline. Here, we consider the role of two common gene variants, FTO and TaqIA rs1800497 in driving gene × environment interactions promoting obesity, metabolic dysfunction, and cognitive change via their influence on DA receptor subtype 2 (DRD2) signaling.

An association study of Taq1A ANKK1 and C957T and - 141C DRD2 polymorphisms in adults with internet gaming disorder: a pilot study

BACKGROUND

Though Internet gaming disorder (IGD) is considered to share similar genetic vulnerability with substance addictions, little has been explored about the role of the genetic variants on IGD. This pilot study was designed to investigate the association of the Taq1A polymorphism of the ankyrin repeat and kinase domain containing 1 (ANKK1) gene and C957T and - 141C of the dopamine D2 receptor (DRD2) with IGD and their role on the personality and temperament traits in IGD among adult population.

METHODS

Sixty-three subjects with IGD and 87 control subjects who regularly played Internet games were recruited. Self-administered questionnaires on self-control, dysfunctional impulsivity, and temperament and character domains were done. The Taq1A ANKK1 and the C957T and - 141C ins/del from the DRD2 genes were genotyped using the specific TaqMan PCR assay.

RESULTS

The distributions of allele and genotype frequencies were not significantly different between the IGD and control groups in both genders. In male, excessive gaming and use of gaming to escape from a negative feeling were associated with the del- genotype of the - 141C. Among IGD, the del+ genotype was associated with higher novelty seeking. Logistic regression showed no predictive value of these polymorphisms for IGD when using age and gender as covariates.

CONCLUSIONS

Though no direct association of the Taq1A ANKK1 and C957T DRD2 variants with IGD were observed, the - 141C polymorphism may play a role in IGD via mediating symptoms or temperament traits.

Alcohol misuse in emerging adulthood: Association of dopamine and serotonin receptor genes with impulsivity-related cognition

Impulsivity predicts alcohol misuse and risk for alcohol use disorder. Cognition mediates much of this association. Genes also account for a large amount of variance in alcohol misuse, with dopamine and serotonin receptor genes of particular interest, because of their role in motivated behavior. The precise psychological mechanisms through which such genes confer risk is unclear. Trait impulsivity conveys risk for alcohol misuse by influencing two distinct domains of cognition: beliefs about the reinforcing effects of alcohol consumption (positive alcohol expectancy) and the perceived ability to resist it (drinking refusal self-efficacy). This study investigated the effect of the dopamine-related polymorphism in the DRD2/ANKK1 gene (rs1800497) and a serotonin-related polymorphism in the HTR2A gene (rs6313) on associations between impulsivity, cognition, and alcohol misuse in 120 emerging adults (18-21years). HTR2A predicted lower positive alcohol expectancy, higher refusal self-efficacy, and lower alcohol misuse. However, neither polymorphism moderated the linkages between impulsivity, cognition, and alcohol misuse. This is the first report of an association between HTR2A and alcohol-related cognition. Theoretically-driven biopsychosocial models have potential to elucidate the specific cognitive mechanisms through which distal risk factors like genes and temperament affect alcohol misuse in emerging adulthood.

Interaction between the obesity-risk gene FTO and the dopamine D2 receptor gene ANKK1/TaqIA on insulin sensitivity

AIMS/HYPOTHESIS

Variations in FTO are the strongest common genetic determinants of adiposity, and may partly act by influencing dopaminergic signalling in the brain leading to altered reward processing that promotes increased food intake. Therefore, we investigated the impact of such an interaction on body composition, and peripheral and brain insulin sensitivity.

METHODS

Participants from the Tübingen Family study (n = 2245) and the Malmö Diet and Cancer study (n = 2921) were genotyped for FTO SNP rs8050136 and ANKK1 SNP rs1800497. Insulin sensitivity in the caudate nucleus, an important reward area in the brain, was assessed by fMRI in 45 participants combined with intranasal insulin administration.

RESULTS

We found evidence of an interaction between variations in FTO and an ANKK1 polymorphism that associates with dopamine (D2) receptor density. In cases of reduced D2 receptor availability, as indicated by the ANKK1 polymorphism, FTO variation was associated with increased body fat and waist circumference and reduced peripheral insulin sensitivity. Similarly, altered central insulin sensitivity was observed in the caudate nucleus in individuals with the FTO obesity-risk allele and diminished D2 receptors.

CONCLUSIONS/INTERPRETATION

The effects of variations in FTO are dependent on dopamine D2 receptor density (determined by the ANKK1 polymorphism). Carriers of both risk alleles might, therefore, be at increased risk of obesity and diabetes.

COMT and ANKK1 Genetics Interact With Depression to Influence Behavior Following Severe TBI: An Initial Assessment

OBJECTIVE

Genetic variations in the dopamine (DA) system are associated with cortical-striatal behavior in multiple populations. This study assessed associations of functional polymorphisms in the ankyrin repeat and kinase domain (ANKK1; Taq1a) and catechol-O-methyltransferase (COMT; Val158Met) genes with behavioral dysfunction following traumatic brain injury (TBI).

PARTICIPANTS

This was a prospective study of 90 survivors of severe TBI recruited from a level 1 trauma center.

MAIN MEASURES

The Frontal Systems Behavior Scale, a self- or family report questionnaire evaluating behavior associated with frontal lobe dysfunction, was completed 6 and 12 months postinjury. Depression was measured concurrently with the Patient Health Questionnaire-9. Study participants were genotyped for Val158Met and Taq1a polymorphisms.

RESULTS

No statistically significant behavioral differences were observed by Taq1a or Val158Met genotype alone. At 12 months, among those with depression, Met homozygotes (Val158Met) self-reported worse behavior than Val carriers (P = .015), and A2 homozygotes (Taq1a) self-reported worse behavior than A1 carriers (P = .028) in bivariable analysis. Multivariable models suggest an interaction between depression and genetic variation with behavior at 12 months post-TBI, and descriptive analysis suggests that carriage of both risk alleles may contribute to worse behavioral performance than carriage of either risk allele alone.

CONCLUSION

In the context of depression, Val158Met and Taq1a polymorphisms are individually associated with behavioral dysfunction 12 months following severe TBI, with preliminary evidence suggesting cumulative, or perhaps epistatic, effects of COMT and ANKK1 on behavioral dysfunction.

Effects of the modern food environment on striatal function, cognition and regulation of ingestive behavior

Emerging evidence from human and animal studies suggest that consumption of palatable foods rich in fat and/or carbohydrates may produce deleterious influences on brain function independently of body weight or metabolic disease. Here we consider two mechanisms by which diet can impact striatal circuits to amplify food cue reactivity and impair inhibitory control. First, we review findings demonstrating that the energetic properties of foods regulate nucleus accumbens food cue reactivity, a demonstrated predictor of weight gain susceptibility, which is then sensitized by chronic consumption of an energy dense diet. Second, we consider evidence for diet-induced adaptations in dorsal striatal dopamine signaling that is associated with impaired inhibitory control and negative outcome learning.

The ANKK1/DRD2 locus is a genomic substrate for affective priming and recognition of angry faces

INTRODUCTION

Ankyrin repeat and kinase domain containing I (ANKK1) and dopamine D2 receptor (DRD2) genes have been associated with psychopathic traits in clinical samples. On the other hand, individuals high in psychopathy show reduced affective priming and deficits in facial expression recognition. We have hypothesized that these emotion-related cognitive phenomena are associated with Taq IA (rs18000497) SNP (single nucleotide polymorphism) of the ANKK1 gene and with C957T (rs6277) SNP of the DRD2 gene.

METHODS

We performed a genetic association analysis in 94 self-reported Caucasian healthy volunteers. The participants completed 144 trials of an affective priming task, in which primes and targets were emotional words. They also had to recognize 64 facial expressions of happiness, sadness, anger, and fear in an expression recognition task. Regarding the genetic analyses, Taq IA and C957T SNPs were genotyped.

RESULTS

We found that the C957T SNP TT genotype was associated with a stronger priming effect and a better recognition of angry expressions. No associations were found for the Taq IA SNP. In addition, in silico analysis demonstrated that C957T SNP is a marker of a regulatory sequence at the 5' UTR of ANKK1 gene, thus suggesting the involvement of the whole ANKK1/DRD2 locus in cognitive-emotional processing.

CONCLUSIONS

These results suggest that affective priming and recognition of angry facial expressions are endophenotypes that lie on the pathway between the ANKK1/DRD2 locus and some deviant phenotypes.

Association between ANKK1 (rs1800497) polymorphism of DRD2 gene and attention deficit hyperactivity disorder: a meta-analysis

The role of dopamine neurotransmitter in attention deficit hyperactivity disorder (ADHD) remains controversial. Many molecular studies focusing on dopamine receptors have attempted to analyze the gene polymorphisms involved in dopaminergic transmission. Of these, rs1800497 (TaqIA) single nucleotide polymorphism (SNP) of the dopamine D2 receptor (DRD2) gene has been focused on by the most attention. However, this locus has recently been identified within the exon 8 of ankyrin repeat and kinase domain containing 1 (ANKK1), giving rise to a Glu713-to-Lys substitution in the putative ANKK1 protein. Thus, we performed a meta-analysis to determine whether ANKK1 polymorphism influences the risk of ADHD and examined the relationship between rs1800497 genetic variant and the etiology of ADHD. Relevant case-control studies were retrieved by database searches and selected according to established inclusion criteria. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to evaluate the strength of the associations. Meta-regression, subgroup analysis, sensitivity analysis and cumulative meta-analysis were performed. A total of 11 studies with 1645 cases and 1641 controls were included. In the dominant model, the rs1800497 locus was associated with ADHD, with a pooled OR of 1.785 (95% CI=1.068-2.984, p=0.027). Subgroup analysis for ethnicity indicated that the polymorphism was associated with ADHD in Africans (OR=3.286, 95% CI=1.434-7.527, p=0.005), but not in East Asians (OR=1.513, 95% CI=0.817-2.805, p=0.188) and Caucasians (OR=1.740, 95% CI=0.928-3.263, p=0.084). However, the results of meta-regression indicated that publication date (p=0.601), source of controls (p=0.685), ethnicity (p=0.755) and diagnostic criteria (p=0.104) could not explain the potential sources of heterogeneity. This meta-analysis indicates that the rs1800497 locus may be associated with ADHD. These data provide possible references for future case-control studies in childhood disorders.

Genes and personality characteristics: Possible association of the genetic background with intelligence and decision making in 830 Caucasian Greek subjects

It is well known that intelligence consists of a variety of interactional and cognitive skills and abilities (e.g. tradecraft; critical and divergent thinking; perception of foreign information). Decision making is defined as the conscious choice between given options, relating to a problem. Both genetic background and environment comprise key elements for personality characteristics of the human being. The aim of this study is to determine the frequency distribution of rs324420, rs1800497, rs363050, rs6265, rs1328674 polymorphisms known to be involved in individual personality characteristics, in 830 Greek Subjects. The study is independent from direct clinical measurements (e.g. IQ measurements; physiological tests). The population of the volunteers is described, based on genotype, sex, with the respective gene frequencies, including the Minor Allele Frequency (MAF). A potential influence of the volunteer gender with the above characteristics (based on genotypes and alleles) is examined and finally, volunteers are classified as follows: A volunteer receives + 1, for each genotype/allele, which enhances his intelligence or his decision-making. In contrast, he receives - 1, for each genotype/allele, which relegates the individual characteristic. No statistically significant gender-characteristics correlation is observed. According to their genetic profile, a rate of 92.5%, of the volunteers may be characterized by prudence and temperance of thought, with only a small proportion of them (7.5%) may be classified as genetically spontaneous and adventurous. Regarding intelligence, the study population may lay around average and a little above it, at a rate of 96.3%, while the edges of the scale suggest only a 0.5% of the volunteers, who, although the "smartest", somehow seem to lack prudence. In conclusion, individuals with low cognitive ability may be more prudent than others and vice versa, while the "smartest" ones tend to be more risky, in decision-making. Therefore, intelligence and decision-making may, after all, be less linked to each other than expected.

Identification of ANKK1 rs1800497 variant in schizophrenia: new data and meta-analysis

One functional polymorphism (rs1800497) within the ankyrin repeat and kinase domain containing-1 gene (ANKK1) was reported to be associated with schizophrenia, but results among different studies vary and conclusions remain controversial. The present study sought to clarify this potential association among a population of Han Chinese with early onset schizophrenia using a case-control (396 patients and 399 controls) and family based study (103 trios). We then performed a meta-analysis (comprising 11 case-control and 2 family-based studies) based on the present literature. Results of the association study revealed no significant difference in allele and genotype frequencies between the cases and controls, and no significant transmission distortion was detected. Kaplan-Meier survival analysis showed that age at onset in schizophrenia was significantly associated with the rs1800497 polymorphism in female patients, but not in males. Female T allele carriers had a lower age at onset than those without T allele (log rank statistic χ(2) = 5.16, P = 0.023; corrected P = 0.046). Meta-analysis results indicated that rs1800497 is not associated with schizophrenia in the overall population (P = 0.77 for the case-control studies; P = 0.06 for the family-based studies). Our results support the hypothesis that rs1800497 polymorphism is likely to have a modifying rather than causative effect on schizophrenia. These findings may represent a significant genetic clue for the etiology of schizophrenia in females, but further investigation is required to clarify the exact role of ANKK1 in the development of schizophrenia.

Who gains? Genetic and neurophysiological correlates of BMI gain upon college entry in women

The present investigation examined P3 event-related electroencephalographic potentials and a short and selected list of addiction-related candidate gene single nucleotide polymorphisms (SNPs) within 84 female students, aged 18-20 yrs. The students were assigned to groups defined by the presence versus absence of a positive body mass index (BMI) change from the pre-college physical exam to the current day. Analyses revealed significantly greater P3 latencies and reduced P3 amplitudes during a response inhibition task among students who exhibited a BMI gain. BMI gain was also significantly associated with a ANKK1 SNP previously implicated in substance dependence risk. In logistic regression analyses, P3 latencies at the frontal electrode and this ANKK1 genotype correctly classified 71.1% of the students into the BMI groups. The present findings suggest that heritable indicators of impaired response inhibition can differentiate students who may be on a path toward an overweight or obese body mass.

A variant in ANKK1 modulates acute subjective effects of cocaine: a preliminary study

This study aimed to evaluate whether functional variants in the ankyrin repeat and kinase domain-containing 1 (ANKK1) gene and/or the dopamine receptor D2 (DRD2) gene modulate the subjective effects (reward or non-reward response to a stimulus) produced by cocaine administration. Cocaine-dependent participants (N = 47) were administered 40 mg of cocaine or placebo at time 0, and a subjective effects questionnaire (visual analog scale) was administered 15 min prior to cocaine administration, and at 5, 10, 15 and 20 min following administration. The influence of polymorphisms in the ANKK1 and DRD2 genes on subjective experience of cocaine in the laboratory was tested. Participants with a T allele of ANKK1 rs1800497 experienced greater subjective 'high' (P = 0.00006), 'any drug effect' (P = 0.0003) and 'like' (P = 0.0004) relative to the CC genotype group. Although the variant in the DRD2 gene was shown to be associated with subjective effects, linkage disequilibrium analysis revealed that this association was driven by the ANKK1 rs1800497 variant. A participant's ANKK1 genotype may identify individuals who are likely to experience greater positive subjective effects following cocaine exposure, including greater 'high' and 'like', and these individuals may have increased vulnerability to continue using cocaine or they may be at greater risk to relapse during periods of abstinence. However, these results are preliminary and replication is necessary to confirm these findings.