Poster I presented at the Schizophrenia International Research Society conference in Florence in April, 2010.Leer menos
![Introduction: Conclusions: Methods: Unit on Dynamic Imaging Genetics, Clinical Brain Disorders Branch, Genes, Cognition, and Psychosis Program, National Institute of Mental Health, National Institutes of Health, Bethesda, MD Imaging Genetics Analyses Subjects were recruited from the Clinical Brain Disorders Branch (CBDB) Sibling Study, and NKCC1 genotyping was performed using the TaqMan 5′-exonuclease allelic discrimination assay. From available healthy subjects with QC+ fMRI data and NKCC1 genotypes specific to the ∆21 transcript (rs13175996, rs3805616, rs10089, rs3087889), there was a sample of 225 Caucasian healthy volunteers. Exclusion criteria included history of psychosis, head trauma, significant medical condition, or current psychiatric medications. The genotype groups were matched for age, gender, WAIS-IQ , N -back reaction time and N -back performance (p > 0.05) ( TABLE 1 ). N-back Task Description Participants performed the N -back task (Callicott et al., 1999). Four 30 sec blocks of 2-back task alternated with 4 blocks of 0-back task. 15 stimuli per block were presented, each lasting 1800 ms. Participants first practiced the task outside the scanner until performance was constant. Imaging Details Whole-brain BOLD fMRI data were collected on a 3 Tesla GE (Milwaukee, WI) scanner (24 interleaved slices, TE = 20, TR = 2, flip angle = 90°, FOV = 24, voxel size = 3.75 x 3.75 x 3.75, matrix = 64 x 64) using Gradient Echo Planar Imaging sequences. fMRI Data Analyses The data were preprocessed and analyzed in SPM5 ( www.fil.ion.ucl.ac.uk/spm , Wellcome Department, London, UK). To explore genotype effects, second level random effects analyses were performed using multiple regression. Analyses were conducted on 8 individual SNPs, as well as a 4 marker haplotype spanning the 3’ region ( FIGURE 2 ), which held individual SNP fMRI positive findings and was associated with mRNA expression levels. Haplotype estimation proceeded as described previously (Nichols et al., 2006) using PHASE (Stephens et al., 2001). Parameter estimates from DLPFC and hippocampus were extracted and graphed in SPSS (Chicago, IL). As a post-hoc step, we reduced the threshold to p < 0.01 and detected differences in activation between groups, since this gene is highly expressed in the hippocampus. We assessed significance using small volume correction for hippocampus and DLPFC (p < 0.05 FWE). Behavioral and Demographic Data A between-groups ANOVA was performed in SPSS with genotype group as an independent variable and age, WAIS-IQ, 2-back reaction time, 2-back accuracy as factors ( TABLE 1 ). ,[object Object],[object Object],[object Object],[object Object],Results: ,[object Object],[object Object],[object Object],[object Object],[object Object],Table 1 Schizophrenia is a disorder of complex heritability (Harrison and Weinberger, 2005). Alterations in GABA-mediated neurotransmission play a major role in schizophrenia. Early in brain development, GABA, the primary inhibitory neurotransmitter in adult brain, is excitatory. This switch from excitation to inhibition is mediated by the relative expression of two genes, NKCC1 (SLC12A2), and KCC2 (SLC12A5), cation chloride cotransporters. Expression of these cotransporters is an essential component of brain development. Our group recently detected four new alternative splice variants of NKCC1 in the human adult and fetal brain (1~27 (21a), 1~27(∆5~26), 1~4a, and 1~2a; FIGURE 1 ). A significant association with the expression of the alternative transcript (NKCC1b (1~27 (∆21)) was found with rs3087889. The A/A genotype predicted lower expression than both the T/A (p=0.044) and T/T (p=0.01) genotypes (Morita et al., in preparation). While there was no strong association signal for any individual SNP (trend level for rs10089 (p=0.01), rs3805616 (p=0.06), rs3087889 (p=0.03)), neuropsychological measures indicated several SNPs, including rs10089 and rs3087889, associated with working memory (WM) (p = 0.006-0.007 and p = 0.01-0.006, respectively). Associations were also found with verbal memory, visual memory, processing speed, card sort, and digit span in siblings of schizophrenic patients possessing what we later determined to be, a risk haplotype. We sought evidence for physiological effects using fMRI in healthy volunteers during an executive WM task to explore the functional impact of our association results (Callicott et al., 2005) . Allelic variation in NKCC1 is associated with hippocampal and dorsolateral prefrontal cortex activation during working memory Lauren R. Testa, Joseph H. Callicott, Yukitaka Morita, Bhaskar Kolachana, Richard E. Straub, Daniel R. Weinberger, Thomas M. Hyde NKCC1 1~27 Figure 2: Location of SNPs on NKCC1 Morita, et al., In Prep. Figure 1: MAF and LD Scores References: 1) Callicott, J.H., et al. (1999). Physiological characteristics of capacity constraints in working memory as revealed by functional MRI. Cerebral Cortex, 9 , 20-6 2) Callicott, J. H., et al. (2000). Physiological dysfunction of the dorsolateral prefrontal cortex revisited. Cerebral Cortex ( 10 )11, 1078-1092. 3) Callicott, J. H., et al. (2003). Complexity of prefrontal cortical dysfunction in schizophrenia: more than up or down. American Journal of Psychiatry , 12 , 2209-2215. 4) Callicott J. H., et al. (2005). Variation in DISC1 affects hippocampal structure and function and increases risk for schizophrenia. Proc National Academy of Science , 102 , 8627-32. 5) Harrison, P.J., and Weinberger, D.R. (2005). Schizophrenia genes, gene expression, and neuropathology: on the matter of their convergence. Molecular Psychiatry, 10, 40-68. 6) Morita et al., in prep. 7) Stephens, M., Smith, N., and Donnelly, P. (2001). A new statistical method for haplotype reconstruction from population data. American Journal of Human Genetics, 68 , 978-979. NKCC1 Genotype Demographics Demographic Data rs13175996 rs10089 rs3805616 rs3087889 Alleles G/G (Non-Risk) A Carriers (Risk) G/G (Non-Risk) A Carriers (Risk) C/C (Non-Risk) T Carriers (Risk) T/T (Non-Risk) A Carriers (Risk) Total 200 25 138 87 159 66 134 91 Age 32 ± 10 32 ± 9 31 ± 9 31 ± 10 32 ± 9 31 ± 10 31 ± 9 32 ± 10 Gender 89 M; 111 F 11 M; 14 F 63 M; 77 F 42 M; 43 F 66 M; 93 F 34 M; 32 F 57 M; 77 F 43 M; 48 F WAIS-IQ 107.7 ± 9.4 109.0 ± 8.2 108.1 ± 8.6 107.2 ± 9.5 107.6 ± 10.1 108.5 ± 6.9 107.4 ± 9.8 108.5 ± 8.5 Years of Education 16.8 ± 2.6 17.7 ± 2.8 17.1 ± 2.5 16.8 ± 3.1 16.9 ± 2.5 17.1 ± 2.9 16.9 ± 2.5 17.1 ± 2.8 2-back Accuracy (%) 82.0 ± 16.3 80.0 ± 17.4 83.0 ± 14.3 80.1 ± 17.9 81.3 ± 15.9 82.8 ± 17.6 82.3 ± 15.6 81.0 ± 17.6 2-back Reaction Time (sec) 0.51 ± 0.23 0.46 ± 0.22 0.50 ± 0.22 0.51 ± 0.22 0.51 ± 0.24 0.49 ± 0.22 0.50 ± 0.23 0.52 ± 0.23 rs12189448 (Int16) rs3087889 (3’-UTR) rs13175996 (Int20) rs10067555 (Int1) rs53805604 (Int4) rs2568928 (Int12) rs3805616 (Int25) rs10089 (3’-UTR ) Figure 3 : rs3805616 - also found for all other SNPs (Risk Carriers > Non-Risk) Figure 5 : 4 SNP Haplotype (Risk Carriers > Non-Risk) Bilateral DLPFC p < 0.05, FWE small volume correction Figure 4: rs3087889 - not seen in any other individual SNP (Risk > Non-Risk) Hippocampus p < 0.05 uncorrected Hippocampus p < 0.005 uncorrected, p = 0.06 FWE small volume correction Bilateral DLPFC p < 0.05, FWE small volume correction Figure 6 : 4 SNP Haplotype (Risk Carriers > Non-Risk)](https://image.slidesharecdn.com/nkcc1posterforsirs10-1272917837407-phpapp01/85/NKCC1-Poster-for-SIRS-2010-1-320.jpg)
