Individual Differences in Relative Telomere Length in Mentally Healthy Subjects: The Effect of TERT Gene Polymorphism and Urban Residency.

The changes in the telomere length caused by the terminal underreplication in the existing literature are related to depressive disorders. However, the use of the telomere length as a biomarker of depressive states is ambiguous, which is due to the effect of various environmental factors on both the psychoemotional state and cellular aging of an organism. In order to identify the possible use of the relative telomere length (RTL) measured in peripheral blood leukocytes as a biomarker of enhanced liability to depression prior to the clinical symptoms, as well as to determine the link between telomere length, sociodemographic factors, allelic variants of the genes involved in the regulation of telomere elongation, and depression level, the association analysis of reverse transcriptase (TERT rs7726159), telomerase RNA component (TERC rs1317082), and the CST complex encoding protein (OBFC1 rs2487999) gene polymorphisms was performed with RTL and depression level in mentally healthy individuals (N = 1065) aged 18-25 years. Together with genetic variants, the examined regression models included various sociodemographic parameters as predictors. As a result of statistical analysis, we failed to observe the association between RTL and individual differences in depression level in the studied sample. Nevertheless, multiple regression analysis allowed us to construct a statistically significant model of individual variance in RTL (P = 4.3е-4; r 2 = 0.018), which included rs7726159 in the TERT gene (P = 0.020; ß = 0.078) and such environmental predictors as age (P = 0.001; ß = -0.027) and place of residence in childhood (urban/rural area) (P = 0.048; ß = 0.063). The data obtained confirm the involvement of TERT gene variants and age in telomere length in mentally healthy individuals aged 18-25 years and indicate a negative effect of urban residency on telomere length shortening, which reflects the cellular aging of an organism.

The role of the KIBRA and APOE genes in developing spatial abilities in humans.

In the contemporary high-tech society, spatial abilities predict individual life and professional success, especially in the STEM (Science, Technology, Engineering, and Mathematics) disciplines. According to neurobiological hypotheses, individual differences in cognitive abilities may be attributed to the functioning of genes involved in the regulation of neurogenesis and synaptic plasticity. In addition, genome-wide association studies identified rs17070145 located in the KIBRA gene, which was associated with individual differences in episodic memory. Considering a significant role of genetic and environmental components in cognitive functioning, the present study aimed to estimate the main effect of NGF (rs6330), NRXN1 (rs1045881, rs4971648), KIBRA (rs17070145), NRG1 (rs6994992), BDNF (rs6265), GRIN2B (rs3764030), APOE (rs7412, rs429358), and SNAP25 (rs363050) gene polymorphisms and to assess the effect of gene-environment interactions on individual differences in spatial ability in individuals without cognitive decline aged 18-25 years (N = 1011, 80 % women). Spatial abilities were measured using a battery of cognitive tests including the assessment of "3D shape rotation" (mental rotation). Multiple regression analysis, which was carried out in the total sample controlling for sex, ethnicity and the presence of the "risk" APOE ε4 allele, demonstrated the association of the rs17070145 Т-allele in the KIBRA gene with enhanced spatial ability (ß = 1.32; pFDR = 0.037) compared to carriers of the rs17070145 CC-genotype. The analysis of gene-environment interactions revealed that nicotine smoking (ß = 3.74; p = 0.010) and urban/rural residency in childhood (ß = -6.94; p = 0.0002) modulated the association of KIBRA rs17070145 and АРОЕ (rs7412, rs429358) gene variants with individual differences in mental rotation, respectively. The data obtained confirm the effect of the KIBRA rs17070145 Т-allele on improved cognitive functioning and for the first time evidence the association of the mentioned genetic variant with spatial abilities in humans. A "protective" effect of the APOE ε2 allele on enhanced cognitive functioning is observed only under certain conditions related to childhood rearing.

[Arginine-vasopressin receptor gene (AVPR1A, AVPR1B) polymorphisms and their relation to personality traits].

The present study aimed to assess the main effects ofAVPRIA (rs11174811, RSI) and AVPRIB (rs28632197, rs33911258) gene polymorphisms, as well as haplotypic, GxE and GxG effects on personality trait variation in 1018 healthy individuals, considering gender and ethnicity confounding. Haplotype analysis revealed an association ofAVPRIA C*S- and C*L-haplotype (rs11174811 and RS1, respectively) and increased (PFDR= 0.016) or decreased (PFDR = 0.031) Extraversion (EPI) in Bashkirs, respectively. The association of AVPR1B G*A-haplotype (rs28632197 and rs33911258, respectively) and decreased Self-transcendence (TCI-125) (P(FDR) = 0.040) was demonstrated in the total sample and in Udmurts. GxE analysis revealed that the birth season modulated the involvement of the AVPR1A (rs11174811) gene marker in the variation of Persistence (TCI-125) in the total sample (P(FDR) = 0.012). The modulating effect of several environmental factors (ethnicity and birth season) on the association of AVPR1A and AVPR1B gene polymorphisms and personality traits was established.