Associations between neurodevelopmental genes, neuroanatomy, and ultra high risk symptoms of psychosis in 22q11.2 deletion syndrome
Item Type Article
Authors Thompson, Carlie A.; Karelis, Jason; Middleton, Frank A.; Gentile, Karen; Coman, Ioana L.; Radoeva, Petya D.; Mehta, Rashi; Fremont, Wanda P.; Antshel, Kevin M.; Faraone, Stephen V.; Kates, Wendy R.
Citation Thompson CA, Karelis J, Middleton FA, Gentile K, Coman IL, Radoeva PD, Mehta R, Fremont WP, Antshel KM, Faraone SV, Kates WR. 2017. Associations Between Neurodevelopmental Genes, Neuroanatomy, and Ultra High Risk Symptoms of Psychosis in 22q11.2 Deletion Syndrome. Am J Med Genet Part B 174B:295–314
DOI 10.1002/ajmg.b.32515
Publisher Wiley
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Item License http://doi.wiley.com/10.1002/tdm_license_1 Link to Item http://hdl.handle.net/20.500.12648/1796 RESEARCH ARTICLE
Neuropsychiatric Genetics Associations Between Neurodevelopmental Genes, Neuroanatomy, and Ultra High Risk Symptoms of Psychosis in 22q11.2 Deletion Syndrome Carlie A. Thompson,1 Jason Karelis,1 Frank A. Middleton,1,2 Karen Gentile,2 Ioana L. Coman,3 Petya D. Radoeva,4 Rashi Mehta,5 Wanda P. Fremont,1 Kevin M. Antshel,1,6 Stephen V. Faraone,1 and Wendy R. Kates1* 1Department of Psychiatry and Behavioral Sciences, SUNY Upstate Medical University, Syracuse, New York 2Department of Neuroscience, SUNY Upstate Medical University, Syracuse, New York 3Department of Computer Science, SUNY Oswego, Oswego, New York 4Department of Psychiatry, University of Washington, Seattle, Washington 5Department of Radiology, SUNY Upstate Medical University, Syracuse, New York 6Department of Psychology, Syracuse University, Syracuse, New York
Manuscript Received: 14 April 2016; Manuscript Accepted: 7 November 2016
22q11.2 deletion syndrome is a neurogenetic disorder resulting in the deletion of over 40 genes. Up to 40% of individuals with How to Cite this Article: 22q11.2DS develop schizophrenia, though little is known about Thompson CA, Karelis J, Middleton FA, the underlying mechanisms. We hypothesized that allelic varia- Gentile K, Coman IL, Radoeva PD, Mehta tion in functional polymorphisms in seven genes unique to the R, Fremont WP, Antshel KM, Faraone SV, deleted region would affect lobar brain volumes, which would Kates WR. 2017. Associations Between predict risk for psychosis in youth with 22q11.2DS. Participants Neurodevelopmental Genes, included 56 individuals (30 males) with 22q11.2DS. Anatomic Neuroanatomy, and Ultra High Risk MR images were collected and processed using Freesurfer. Symptoms of Psychosis in 22q11.2 Deletion Participants were genotyped for 10 SNPs in the COMT, Syndrome. DGCR8, GNB1L, PIK4CA, PRODH, RTN4R, and ZDHHC8 genes. All subjects were assessed for ultra high risk symptoms Am J Med Genet Part B 174B:295–314. of psychosis. Allelic variation of the rs701428 SNP of RTN4R was significantly associated with volumetric differences in gray matter of the lingual gyrus and cuneus of the occipital lobe. 2008]. The typically deleted region (TDR) is 3 Mb, found in Moreover, occipital gray matter volumes were robustly associ- approximately 87% of cases [Shaikh et al., 2000]. Low-copy ated with ultra high risk symptoms of psychosis in the presence DNA repeats (LCRs) specific to chromosome 22 have been impli- of the G allele of rs701428. Our results suggest that RTN4R, a cated in the formation of 22q11.2 deletions and are found in relatively under-studied gene at the 22q11 locus, constitutes a proximity to the end-points of the TDR [Shaikh et al., 2000]. It susceptibility gene for psychosis in individuals with this syn- has been hypothesized that homologous recombination errors drome through its alteration of the architecture of the brain. between these LCRs during meiosis results in the deletions (and Ó 2017 Wiley Periodicals, Inc. duplications) found in the sequences of individuals with 22q11.2DS [Edelmann et al., 1999]. Key words: velo-cardio-facial syndrome; RTN4R; axonal development; Freesurfer; schizophrenia Conflicts of interest: The authors have no conflicts of interest to declare. Grant sponsor: National Institutes of Health; Grant number: MH064824. Correspondence to: Wendy R. Kates, Ph.D., Department of Psychiatry and Behavioral INTRODUCTION Sciences, State University of New York at Upstate Medical University, 750 East Adams Street, Syracuse, New York. 22q11.2 deletion syndrome (22q11.2DS) is the most common E-mail: [email protected] micro-deletion syndrome found in humans [Edelmann et al., Article first published online in Wiley Online Library 1999]. The size of the region deleted can vary but almost always (wileyonlinelibrary.com): 31 January 2017 spans a shared minimal deletion region of 1.5 Mb [Maynard et al., DOI 10.1002/ajmg.b.32515
Ó 2017 Wiley Periodicals, Inc. 295 296 AMERICAN JOURNAL OF MEDICAL GENETICS PART B
Individuals with 22q11.2DS have increased susceptibility to glutamate [Bender et al., 2005]. Alterations in glutamate signaling behavioral, anxiety and mood disorders, and psychosis [Schneider are very well-established as risk factors for psychosis [Moghaddam et al., 2014]. In particular, they have over a 30% chance of and Javitt, 2012]. We examined the SNP, rs4819756 (A/G), as noted developing schizophrenia, which is considerably higher than the in Table I. worldwide population risk of less than 1% [Murphy et al., 1999; The ZDDHC8 gene, located in the distal third of the 1.5 Mb- Saha et al., 2005; Green et al., 2009; van Os and Kapur, 2009]. minimal deletion region [Maynard et al., 2008], is broadly Consequently, there has been considerable interest in determining expressed in many regions of the adult human brain [Mukai which genes in the TDR might contribute to the elevated risk for et al., 2004], particularly in the olfactory bulb, neocortex, and schizophrenia. Several genes for which individuals with 22q11.2DS cerebellum [Maynard et al., 2008], as well as the adult mouse brain are hemizygous have been linked to the development of schizo- [Mukai et al., 2004]. Among 72 known SNPs located within the 1.5- phrenia in both individuals with this syndrome and the population Mb deleted region, a polymorphism in ZDDHC8, known as at large [Chen et al., 2004a,b; Mukai et al., 2004; Gothelf et al., 2005, rs175174, had the greatest association with schizophrenia [Mukai 2011; Budel et al., 2008; Jungerius et al., 2008; Vorstman et al., 2009; et al., 2004]. This polymorphism mediates the alternative splicing Kempf et al., 2008]. However, data supporting the association of ZDDHC8 such that intron 4 is included in the final mRNA between individual genetic variants and risk for psychosis are not transcript; when this intron is retained, a premature stop codon is consistent, most likely due to the relatively distal relationship introduced into the growing amino acid chain that could terminate between genetic variants and psychopathological behaviors translation and result in a truncated protein with diminished [Meyer-Lindenberg and Weinberger, 2007], and the evidence activity [Mukai et al., 2004]. that multiple genes most likely confer small effects on risk for The Reticulon 4 receptor, also known as the Nogo-66 receptor psychiatric disease [Manolio et al., 2009]. It has been suggested that (NgR), is a glycosylphosphatidylinositol (GPI)-linked protein a more fruitful approach would include the examination of inter- encoded by the RTN4R gene, which is located within the distal mediate phenotypes. In this context, intermediate phenotypes are third of the minimal 1.5-Mb deletion region [Maynard et al., 2008]. biologically—based traits or mechanisms through which genes Through interacting with Nogo-66 (Neurite Outgrowth Inhibitor might affect behavior [Meyer-Lindenberg and Weinberger, 66), the receptor plays a significant role in the inhibition of myelin- 2007]. Since neuroanatomic structure is considered such an inter- mediated axonal growth [Fournier et al., 2001]. Nogo-66 localizes mediate phenotype, we sought to examine the extent to which to axons and binds to oligodendrocyte-myelin glycoprotein allelic variants of candidate genes alter neuroanatomic structure to (OMgp), myelin-associated glycoprotein (MAG), and Nogo-A increase the risk for psychosis in individuals with 22q11.2DS. Here (RTN4), all of which inhibit axonal sprouting. The Nogo-66 we describe briefly the functions of the seven candidate genes at the receptor, together with other GPI-linked axonal proteins, is re- 22q11.2 locus that we examined, all of which are expressed in brain quired for Nogo-66 to retain its inhibitory functions [Fournier and implicated in schizophrenia. Table I summarizes studies that et al., 2001]. Nogo-66 collapses the axonal growth cones found in have examined the clinical and, if available, neuroanatomic studies the dorsal root ganglion and inhibits neurite outgrowth [Fournier that justify the inclusion of each gene in the current study. et al., 2001]. Due to its potential role in plasticity and neuronal The COMT gene is located in the 1.5 critical deletion region that regeneration, the Reticulon 4 receptor is being researched as a is consistently deleted in cases of 22q11.2DS. Its protein product, possible drug-target for spinal and cerebrovascular injury [Baptiste the COMT enzyme (EC 2.1.1.6), catabolizes catecholamines— and Fehlings, 2007]. We have previously reported that the rs701428 dopamine, norepinephrine, and epinephrine. The COMT gene SNP in RTN4R is associated with alterations in white matter encodes both membrane-bound and soluble COMT enzyme microstructure the anterior limb of the internal capsule (ALIC) (MB-COMT and S-COMT, respectively), with the former being in individuals with 22q11.2DS (Table I). the predominant form in the brain [Bertocci et al., 1991; Chen et al., PIK4CA is an enzyme that helps to regulate signal transduction 2004a]. The COMT enzyme, along with monoamine oxidase A in neurons and synaptic transmission. It is expressed in gray (MAOA), has a particularly strong influence on dopamine metab- matter, though at lesser levels in the adult human brain than in olism, particularly in the prefrontal cortex [Tunbridge et al., 2004; fetal brain, potentially indicative of the neurodevelopmental role Tunbridge et al., 2006], where there is a relatively low concentra- PIK4CA could have [Vorstman et al., 2009]. As noted in Table I, tion of dopamine transporters and thus a need for an alternate way PIK4CA is associated with the development of schizophrenia in to clear dopamine from synapses. We examined a functional both individuals with and without 22q11.2DS [Vorstman et al., polymorphism at codon 158 of the MB-COMT enzyme, consisting 2009]. of the substitution of valine with methionine, that results in a DiGeorge Critical Region gene 8 (DGCR8), also known as Pasha, change from high to low enzymatic activity. As noted in Table I, this is essential to the processing of micro RNA molecules (miRNAs), single nucleotide polymorphism (SNP; rs4680) alters functions which are single-stranded mRNA segments that are typically 22- governed by the prefrontal cortex and has been implicated, albeit nucleotides in length [Sun et al., 2009; Brzustowicz and Bassett, inconsistently, in schizophrenia. 2012; Sellier et al., 2014; Zhao et al., 2015], and which have been PRODH, which codes for proline dehydrogenase, is also implicated in schizophrenia. They are the component of the RNA- located within the 1.5-mb critical deletion region of 22q11.2DS induced silencing complex (RISC) that enables the recognition of [Squarcione et al., 2013]. Proline is an intermediate in the biosyn- specific mRNA segments [Brzustowicz and Bassett, 2012; Forstner thesis of glutamate [Phang et al., 2001], and proline dehydrogenase et al., 2013; Sellier et al., 2014; Zhao et al., 2015]. It has been catalyzes the rate-limiting step in the conversion of proline to proposed that the miRNA/RISC system of post-transcriptional HMSNE AL. ET THOMPSON
TABLE I. Studies Involving SNPs of Interest and Relevant Findings
Pathology/Patient (N) Average Age Gene/Allele Study (Year) per genotype Control (N)/genotype (Years) Summary DGCR8 Zhou et al. SCZ: 256 C: 252 (Chinese) SCZ: 28.44 12.51 Did not observe significant difference in genotype between SCZ and C rs3757 (A/G) [2013] AA: 11, AG: 76, GG: 169 AA:3,AG: 73, GG: 176 C: 30.73 15.5 but did note a significantly heightened risk of SCZ due to the recessive AA genotype.
GNB1L Williams et al. UK case-control: UK case-control: UK case-control: Though a number of SNPs were analyzed, rs5746832 and rs2269726 rs5746832 (A/G) [2008] SCZ: 662, SCZaff spectrum C: 1416 SCZ: 44 15 resulted in the strongest signals. In the UK case-control study, rs2269726(C/T) phenotype: 233 1958 birth cohort control C: 42.4 11.1 observed a male-specific genotype association in TBX1/GNB1L that German case-control: sample: 1421 (rs2269726 German case-control: was replicated in two other case-control studies. The Bulgarian trio SCZ: 513 only) SCZ: 38 sample also reinforced this finding. The 22q11.2DS sample also Bulgarian SCZ trio: German case-control: C: 49 provided evidence of a male-specific association between the SNP SCZ: 480 + parents C: 1330 Bulgarian trio: and psychosis. Genetic markers implicated in psychosis were 22q11.2DS: 83 (22 with SCZ: 33 8 associated with GNB1L expression alterations (using allele specific psychotic episodes) Fathers: 61 9 expression analysis). Mothers: 58 9
Ishiguro et al. rs5746832: rs5746832: SCZ: 48.9 14.5 Using Australian (10 SCZ, 10 C) and Japanese (43 SCZ, 11 C) post- [2010] SCZ: AA: 501, AG: 958, GG:430 AA: 484, AG: 916, GG:476 C: 49.0 14.3 mortem brain samples, observed reduced GNB1L expression levels rs2269726: rs2269726: in the prefrontal cortex of SCZ samples (these patients were not SCZ: TT: 338, TC: 896, CC: 671 TT: 309, TC: 911, CC: 686 genotyped for either SNP). No other gene expression levels differed significantly between cases and controls.No significant association between genotype and SCZ was observed. Did not observe any male- specific associations between genotype and SCZ as Williams et al. observed.
Li et al. [2011] BPD: 1135, MDD: 1135, SCZ: 1135 C: 1135 BPD: 36.6 Both SNPs were associated with BPD with rs5746832 demonstrating a (Chinese Han) rs5746832: MDD: 35.1 stronger association (p¼0.0001). Both SNPs were also associated rs5746832: A: 1175, G: 997 SCZ: 35.4 with SCZ but neither were linked to MDD. BPD: A: 1372, G:820 rs2269726: MDD: A: 1273, G: 932 C: 1272, T: 862 SCZ: A: 1059, G: 985 rs2269726: BPD: C: 1394, T: 758 MDD: C: 1383, T: 851 SCZ: C: 1296, T: 742
PIK4CA Jungerius et al. SCZ: 310 C: 880 (from two cohorts) N/A In the first stage of the study, rs165793 was the only SNP to survive rs165793 (A/G) [2008] rs2072513: rs2072513: correction following analyses comparing allele frequencies of 741 rs165862 (G/T) C: 271, T: 349 G: 584; A: 1192 SNPs within 138 myelin-related genes in a portion of both SCZ and C rs2072513 (C/T) rs165862: rs165862: groups. When more controls were added, association analyses G: 351, T: 269 G: 839; T: 945 revealed four SNPs from PIK4CA (including rs2072513, rs165862, rs165793: rs165793: rs16579) that passes correction. Observed protective TTA haplotype. G: 540, A:80 C: 1208; T: 322 In conclusion, this study demonstrated that in the Dutch population, PIK4CA is significantly associated with risk of SCZ.
(Continued) 297 298 TABLE I. (Continued) Pathology/Patient (N) Average Age Gene/Allele Study (Year) per genotype Control (N)/genotype (Years) Summary Vorstman et al. 22q11.2DS SCZ: 32 22q11.2DS C (no SCZ): 47 SCZ: 40.0 8.7 The three PIK4CA variants were significantly associated with SCZ in an [2009] rs2072513: rs2072513: C: 30.0 9.4 adult 22q11.2DS sample. This study corroborated findings from the C: 15; T:17 C: 13; T:32 Jungerius et al. [2008] study such that a protective TTA haplotype rs165862: rs165862: was again revealed. The G-allele was observed significantly more in G: 22; T:10 G: 22; T:25 SCZ cases; IQ between rs165793 G- and A-allele carriers did not rs165793: rs165793: differ significantly, indicating that the variant more likely impacts G: 32; A 0 G: 36; A:11 brain function related to 22q11.2DS.
Ikeda et al. 22q11.2DS with psychotic 22q11.2DS without psychotic Cases: 31.0 11.0 This study could not genotype rs165862 and used a proxy SNP instead [2010] episode: 83 SCZ, BPD with episode: 59 C: 31.0 11.0 (rs165863). Did not find any evidence that rs165793 was psychotic features, atypical rs2072513: associated with SCZ despite earlier studies demonstrating psychosis (specifically SCZ) C: 13; T:34 relationships between the pathology and SNP in both 22q11DS and rs2072513: rs165793: general populations. C: 7 (6); T: 13 (10) G: 38; A:9 rs165793: G: 17 (14); A 3 (2)
RTN4R Meng et al. Han Chinese SCZ: 707 C: 689 SCZ: 46.98 13.57 Using both a case-control study and transmission disequilibrium test rs701428 (A/G) [2007] GG: 224, AG: 337, AA: 100 GG: 194, AG: 364, AA: 97 C: 33.61 9.01 (TDT), no significant differences were observed between SCZ and C TDT study: 372 family trios (SCZ TDT probands: group in either allele frequencies or genotype. and biological parents) 24.88 6.82
Budel et al. Case-control: Case-control: N/A Rs701428 was weakly associated with SCZ in the Caucasian group; the [2008] SCZ Caucasian: 336 C Caucasian: 300 A-allele (minor) was more prevalent in the SCZ group. SCZ African-American: 196 C African-American: 100 Frequency of minor A-allele: Frequency of minor A-allele: 0.402 0.344 Chinese Trios: Chinese Trios:
SCZ: 621 C: 501 GENETICS MEDICAL OF JOURNAL AMERICAN
Perlstein et al. 22q11.2DS: 99 C: 21 22q11.2DS: 18.0 1.6 rs701428 was significantly associated with differences in DTI [2014] rs701428: SIB: 26 C: 18.1 1.6 metrics (FA and RD) in the ALIC between the control and the A: 11; G: 28 Total: 47 (groups did not differ 22q11.2DS group. Various DTI metrics were also associated with in DTI metrics and positive prodromal symptoms of psychosis in the patient group. were combined accordingly) Increased FA and decreased RD of the ALIC were also associated No genetic data on controls. with the rs701428 G allele in the hemizygous 22q11.2DS group.
Isobe et al. No patient sample used Healthy individuals: 50 AA/AG: 25.7 6.6 In this healthy sample, variation at rs701428 was associated with [2015] AA/AG:36 GG: 24.1 5.3 changes to the corpus callosum, such that participants carrying the GG:14 A allele had larger total corpus callosum volumes than G homozygous counterparts. A allele carries also had lower RD in the central portion of the corpus callosum.
(Continued) B PART HMSNE AL. ET THOMPSON TABLE I. (Continued) Pathology/Patient (N) Average Age Gene/Allele Study (Year) per genotype Control (N)/genotype (Years) Summary ZDHHC8 Mukai et al. “Extended sample of 389 families N/A Afrikaner probands: rs175174 modifies the retention of intron 4, regulating transcription. rs175174 (A/G) [2004] from the US and South Africa +19 years Observed a gender-specific role, such that the A allele was that included the families significantly over transmitted to females and not males. described in our original study”
Afrikaner parent-proband trio: 93 probands (+19y), met DSM-VI criteria for SCZ/SCZaff + biological parents
Chen et al. Case-control: Case-control: Case control: ZDHHC8 SNPs rs175174 and rs175179 were in linkage disequilibrium [2004b] SCZ: 465 C: 467 SCZ: 46.39 12.87 with one another. Both SNPs were associated with schizophrenia, GG: 223, GA: 200, AA:42 GG: 163, GA: 234, AA: 70 C: 29.10 9.98 however, in contrast with the Mukai et al. [2004] study, the G allele Family-based: Family-based: Family-based: (not A) was the observed schizophrenia susceptibility allele. SCZ: 158 Biological parents of family- SCZ: 23.68 6.60 Estimated allele frequencies (%): based SCZ sample G: 69.0, A: 31.0
Saito et al. Japanese SCZ population: 561 Japanese C population: 529 SCZ (F): 49.6 16.4 Did not observe any association between rs175174 and SCZ. No [2005] GG: 238, GA: 245, AA: 78 C: 529 SCZ (M): 47.0 14.9 gender-specific role was observed either. C (F): 39.7 15.4 C (M): 34.9 12.4
Glaser et al. Bulgarian proband-parent trio: Case-control panel (genotype Bulgarian proband- No association between rs175174 and SCZ was observed in any of the [2005] 474 probands and parents frequency): parent trio: samples. Additionally, there was no evidence for sex-related Provides “transmission pattern of Germany C: 789 Proband: 33 8 transmission differences or transmission distortion in any of the A-allele” AA:.39,AG: .45, GG: .16 Father: 61 9 groups. Case-control panel (genotype Poland C: 311 Mother: 58 9 frequency): AA:.35,AG: .47, GG: .18 Case-control panel: Germany SCZ: 606 Sweden C: 153 Germany: AA: .39, AG: .47, GG:.14 AA:.39,AG: .48, GG: .13 SCZ: 37 11 Poland SCZ: 280 C: 43 16 AA: .36, AG: .47, GG: .17 Poland: Sweden SCZ: 142 SCZ: 32 11 AA: .37, AG: .49, GG: .14 C: 44 10 Sweden: SCZ: 44 17 C: 44 16
Otani et al. Japanese population: BPD-C: 298 BPD: 52.5 13.7 No association was found between ZDHHC8 SNPs (including rs175174) [2005] BPD: 171 GG: 106, GA: 154, AA: 38 BPD-C: 50.6 17.7 and BPD or SCZ, corroborating Saito et al. [2005] study involving GG: 65, GA: 82, AA: 24 SCZ-C: 497 SCZ: 45.6 13.9 another Japanese population. Did not identify any gender effects SCZ: 407 GG: 179, GA: 254, AA: 64 SCZ-C: 53.0 14.7 associating ZDHHC8 with SCZ or BPD. GG: 157, GA: 194, AA:56
(Continued) 299 300 TABLE I. (Continued) Pathology/Patient (N) Average Age Gene/Allele Study (Year) per genotype Control (N)/genotype (Years) Summary Faul et al. German SCZ proband-parent triad: Case-control: German probands: Results of the triad portion of the study indicated that the G-allele was [2005] 204 + biological parents C:186 32.4 8.8 preferentially transmitted to females, while the A-allele was AA: 83, AG: 95, GG:26 AA: 71, AG: 93, GG: 22 Case-control SCZ: transmitted to males when parents are heterozygous. The case- Case-control: 39.2 13.5 control portion of the study however, did not support a gender- SCZ: 433 C: 30.0 10.3 specific role in transmission. AA: 154, AG: 219, GG:60
Ota et al. SCZ: 282 C: 379 SCZ: 36.85 10.64 No association was observed between genotype and schizophrenia. [2013] Minor G-allele frequency: 0.4344 Minor G-allele frequency: C: 41.29 15.34 Variation at rs175174 was significantly associated with frontal, SCZ with MRI: 138 0.4393 cerebellar and parietal lobe GMV. Specifically, homozygous G-allele AA: 52, AG: 60, GG:26 carriers showed reduced GMV in the frontal lobe compared to A-allele carriers. Carriers of the G-allele also presented with decreased GMV in cerebellar hemispheres compared to homozygous A-allele counterparts. Participants carrying the A-allele compared to the homozygous G genotype had reductions in GMV in the posterior parts of the brain.
PRODH Kempf et al. Genetic study: Genetic study: Functional Haplotype The rs4819756 A-allele (minor allele) was negatively associated with rs4819756 (A/G) [2008] SCZ probands: 303 SCZ proband unaffected Demographics: SCZ. Observed a significant positive association between SCZ and a siblings/parents + 370 C VBM / Nback: discovered risk haplotype including the rs4819756 major allele, in Did not include specific allelic Neuroimaging control data set: Reference: 30.9 8.0 addition to two other SNPs on the PRODH gene (rs2870983 major distribution data for either Healthy Controls / 31.7 9.1 allele and rs450046 minor allele), creating the risk haplotype GCC. A group Risk: 38.4 12.4 / negative association (protective haplotype) was also observed with 41.7 9.9 the rs4819756 minor allele, and the rs2870983 and rs450046 Protective: 29.7 7.8 reference alleles (ACT). Reductions in GMV in the control group were / 31.7 9.6 associated with the risk haplotype, though they were confined to the Negative Control neostriatum.
Haplotype GENETICS MEDICAL OF JOURNAL AMERICAN Demographics: VBM / Nback: Reference: 32.5 10.1 / 32.5 11.2 Risk: 27.0 7.3 / 27.5 8.3 Protective: 33.0 7.7 / 32.7 8.3
Ota et al. SCZ: 192 C: 179 SCZ: 35.68 10.38 rs4819756 was not associated with SCZ. The SNP did differentiate from [2014] GG: 108, GA: 55, AA:11 GG: 83, GA: 68, AA: 24 C: 38.29 12.88 the predicted Hardy-Weinberg equilibrium value for both study group. Additionally, rs4819756 was not associated with any neuroanatomic measurements.
(Continued) B PART HMSNE AL. ET THOMPSON TABLE I. (Continued) Pathology/Patient (N) Average Age Gene/Allele Study (Year) per genotype Control (N)/genotype (Years) Summary PRODH x COMT Radoeva et al. 22q11.2DS: 46 (42 F, 45 M) N/A Females: 13.5 3.5 Did not observe any effects between COMT or PRODH variants on ASD [2014] rs4819756: A: 34, G: 49 Males: 13.8 3.4 diagnosis in a 22q11.2DS population. Did observe an interaction, rs4680: A: 35, G:52 such that the low-activity alleles (A-A) of both SNPs, were more likely rs4819756-rs4680: A-A: 12, to result in an ASD diagnosis. G-G:28
COMT Murphy et al. 22q11.2DS: 48 (15 with SCZ: 12 22q11.2DS: Results did not support notion that the Met-allele (low activity) was rs4680 (A/G) [1999] psychosis, 35 without C: 316 31.0 10.0 associated with SCZ. psychosis) SCZ: 34.0 12.0 Non-22q11.2DS: 2 (may have C: 40.0 12.0 smaller deletion, point deletion, other form of mutation)
Egan et al. SCZ: 175 HS: 219 SCZ: 36.1 8.5 COMT genotype was not associated with general intelligence, but was [2001] Family-based trios: 104 C: 55 HS: 35.8 8.8 associated with performance on executive cognition related to the Listed demographics by C: 33.9 9.2 prefrontal cortex, independent of psychiatric diagnosis. The Met genotype, no raw genotype allele was associated better performance cognitively. fMRI was used data to examine genotype on prefrontal physiology while completing a working memory task. Again, the Val allele load was not as efficient as the Met in predicting an efficient physiological response. In a family-based sample, the Val allele was transmitted significantly more in SCZ offspring. Taken together, these data indicate that the Val allele increases risk for SCZ.
Shifman et al. Ashkenazi Jew SCZ C (Ashkenazi Jew + patients N/A Observed a moderately significant association between Val (G/G- [2002] sample with other diseases sample): genotype) and schizophrenia in a population of male Ashkenazi Female: 262 Female: 706 Jews. Allelic and genotypic frequency differences were observed on % G/G : 26.3, % A/G : 54.2, %G/G: 25.9, % A/G : 49.7, a gender basis. % A/A : 19.5 % A/A : 24.4 Male: 458 Male: 2264 % G/G : 31.9, % A/G : 47.8, %G/G: 25.8, % A/G : 52.6, % A/A : 20.3 % A/A : 21.6
Goldberg et al. SCZ: 74 HS: 108 SCZ: 37 8 Homozgyous Met participants had the highest n-back scores, while Val [2003] C: 68 HS: 37 9 homozygotes had the lowest. Observed similar results using 1- and C: 35 10 2- back conditions; siblings had significantly lower performance than unrelated controls. No genotype association was seen on Continuous Performance Test.
Kremer et al. Palestinian Arab SCZ triad (case- C: 77 SCZ: 34.8 13.6 The case-control study revealed an association between the Val (high [2003] control and family-based): GG: 14, GA: 39, AA:24 C: 39.5 15.5 activity) allele and schizophrenia. The case-control study also SCZ probands (from 248 nuclear No familial genotype exposed a sex effect; a weak association was observed between the families: 276 information presented. Val allele and the conferred risk of SCZ in females. GG: 77, GA: 136, AA:63
(Continued) 301 TABLE I. (Continued) 302 Pathology/Patient (N) Average Age Gene/Allele Study (Year) per genotype Control (N)/genotype (Years) Summary Sazci et al. SCZ: 297 C: 341 SCZ: 41.22 9.43 There was a significant difference in both genotype and allele [2004] GG: 88, GA: 146, AA:63 GG: 97, GA: 205, AA:39 C: 40.94 8.11 frequenciesbetweenSCZandC(SCZpatientspresentedwiththe Met allele more frequently). Results indicated a significant association between the homozygous Met (low activity) genotype and SCZ. Observed a difference in allelic distribution and SCZ based on sex (Met allele was observed more frequently in women with SCZ).
Fan et al. SCZ: 862 C: 928 SCZ: 39.8 12.0 Using an association study, found no significant association [2005] GG: 491, GA: 316, AA:55 GG: 505, GA: 358, AA: 65 C: 38.3 11.7 between the Val (high activity) allele and SCZ. Participants with SCZ in the association study did present with the Val allele more frequently, however this relationship was not significant. A meta- analysis was also conducted and concluded that heterogeneity among study groups was significant. No significant associated was observed between SCZ and the Val allele in an Asian nor European population.
Gothelf et al. 22q11.2DS: 24 C (age, gender, ethnicity and 22q11.2DS T1: Observed reductions in prefrontal cortex volume accompanied by [2005] G: 11, A:13 IQ-matched with idiopathic 13.3 3.7 impaired cognition in 22q11.2DS participants with the Met allele, developmental disabilities): 22q11.2DS T2: who already suffer from COMT deficiency by way of hemizygosity 23 18..1 3.4 due to the deletion. The low-activity Met allele was also associated No genotyping data for C C T1: 12.5 3.1 with the emergence of various psychotic symptoms during C T2: 17.9 3.3 adolescence.
Smolka et al. N/A C: 35 C: 40.6 7.6 Activation of the brain from pleasant stimuli was not related to [2005] GG: 10, GA: 16, AA:9 genotype, but activation resulting from negative stimuli was. Specifically, a positive correlation was observed between the number of Met alleles and the limbic system, connected prefrontal regions, and visuospatial attention system. Genotype accounted for
38% of interindividual variance observed in BOLD response due to GENETICS MEDICAL OF JOURNAL AMERICAN unpleasant stimuli.
Kates et al. 22q11.2DS: 58 N/A F (26): 11.0 2.5 Results suggested that rs4680 may impact neuroanatomy, specifically [2006b] G: 32, A: 26 M (32): 11.1 2.9 in the dorsal and orbital prefrontal cortices of children with 22q11.2DS. Females with the Met allele and males with the Val allele presented with reduced orbital frontal volumes and larger dorsal prefrontal volumes than female/Val and male/Met counterparts.
Ohnishi et al. SCZ (Japanese): 47 C (Japanese): 67 SCZ GG: 45.98 15.29 A reduction of volume was observed in limbic and paralimbic systems, [2006] GG: 19, GA: 22, AA:6 GG: 38, GA: 25, AA:13 SCZ Met carrier: neocortical areas, and subcortical regions of participants with SCZ. 43.05 10.57 Compared to Met homozygotes (A/A), Val homozygotes (G/G) GA and AA were combined to C GG: 41.47 13.42 presented with volumetric reductions in the left anterior cingulate ‘Met-carrier group’ in both C Met carrier: cortices and right middle temporal gyrus that reached significance. samples because of small 39.26 10.6 Within the SCZ group, in comparison to the Met homozygous SCZ, Val number of Met-homozygotes homozygotes presented withreduced volumes in the bilateral
anterior cingulate cortices, left amygdala-uncus, right middle B PART temporal gyrus, and left thalamus that again, reached significance. (Continued) HMSNE AL. ET THOMPSON TABLE I. (Continued) Pathology/Patient (N) Average Age Gene/Allele Study (Year) per genotype Control (N)/genotype (Years) Summary Heinz and N/A (Review) N/A (Review) N/A (Review) Examined impact of rs4680 on central processing during various tasks Smolka (pertaining to working memory, attentional control and emotion); [2006] utilized fMRI. Met carriers showed a prefrontal cortex-centered response during working memory tasks, and a cingulate cortex- focused response during attentional control tasks. The authors conclude that processing speed in the prefrontal cortex and cingulate may become more efficient as a result of the Met allele. A positive correlation was observed between reactivity to unpleasant visual stimuli (emotional task) at number of Met alleles (both in the amygdala and in limbic and paralimbic nodes). The authors suggest that this result may be the result of reduced emotional resilience to various states of negative mood in individuals containing a higher Met load. In conclusion, while the Met allele may be advantageous to carriers during both attention-related and working memory tasks, the Val allele is preferable in emotional response pertaining to negative stimuli.
McIntosh et al. Genetic high-risk (HR) SCZ: 78 C: 15 HR-NS (GG, GA, AA): In a sample of participants who were considered genetically at high [2007] HR-NS (No Symptoms): 35 GG:3,GA:8,AA:4 20.9 2.8, risk for SCZ (had a previous diagnosis of SCZ in addition to having GG:6,GA: 17, AA:12 21.6 2.9, family member with SCZ), the Val allele was associated with a higher HR-S (with Symptoms): 32 22.7 3.1 risk of SCZ. Reductions in the density of gray matter were also GG:5,GA: 14, AA:13 HR-S (GG, GA, AA): observed, specifically in the anterior cingulate cortex, of participants HR-SCZ (SCZ): 11 18.9 2.9, with the Val allele. GG:7,GA:3,AA:1 21.5 2.9, 21.6 2.8 HR-SCZ (GG, GA, AA): 19.4 2.1, 18.8 3.7, 16.3 (incalculable) C(GG, GA, AA): 22.0 1.6, 21.3 3.0, 21.9 2.2
Bassett et al. 22q11.2DS: 73 N/A 22q11.2DS: In the SCZ subjects, the Met allele was not significantly more [2007] G: 36, A:37 33.8 10.1 prevalent. The Met allele was associated with significantly worse SCZ (within the 22q11.2DS performance on several frontal cognitive tests and did result in sample): 33 more severe excitement symptoms (e.g. poor impulse control, G:13, A:20 uncooperativeness). Though COMT may be involved in frontal functioning within this sample, it has no association with schizophrenia prevalence.
(Continued) 303 TABLE I. (Continued) 304 Pathology/Patient (N) Average Age Gene/Allele Study (Year) per genotype Control (N)/genotype (Years) Summary Gothelf et al. 22q11.2DS (Total sample, C (22q11.2DS without 22q11.2DS (all): Observed an association between the low-activity Met allele in subjects [2007a] including controls): 55 psychiatric diagnosis): 24 16.6 10.2 with ADHD, and in those with OCD, such that the Met allele was G: 44%, A: 56% G: 16, A:8 With ADHD: observed more frequently in participants with these psychiatric With ADHD: 23 16.68 13.0 diagnoses. 4/5 of the SCZ/SZaff participants carried the Met allele, G:6,A:17 With OCD: however, this did not reach significance compared to controls. With OCD: 14 20.87 13.43 G:3,A:11 With SCZ/SZaff: With SCZ/SZaff: 5 27.09 12.68 G:1,A: 4 C: 15.37 6.87 Note: there were several comorbid diagnoses, which is why n does not add up to 55.
van Amelsvoort 22q11.2DS: 26 N/A 22q11.2DS Val: Significantly larger frontal lobe volumes were observed in Val- et al. G: 14, A:12 30.3 10.6 hemizygous subjects; grey matter density was also increased [2008] 12 people from sample had SCZ 22q11.2DS Met: (cerebellum, brainstem, and parahippocampal gyrus) and white G:5,A:7 37.33 10.6 matter density was reduced (cerebellum) in Val-hemizygotes. COMT genotype did not significantly impact neurocognitive performance.
Honea et al. N/A C: 151 C: 32.9 9.7 Variation at rs4680 resulted in volumetric differences to gray matter [2009] GG: 38, GA: 78, AA:35 in frontal and medial temporal areas. Both Val carriers and homozygotes presented with reduced volume in the left hippocampal and parahippocampal gyrus compared to Met homozygotes.
Gothelf et al. 22q11.2DS: 19 C: 18 22q11.2DS: Having greater reduction in the left dorsal prefrontal cortical (dPFC) [2011] G:8,A: 11 Did not genotype controls Time 1:13.05 3.96 GMV was predictive of psychotic symptoms (at Time 2) in Time 2: 17.92 3.81 22q11.2DS subjects. The subject group presented with significantly C: reduced dPFC at both Times 1 and 2 compared to controls.
Time 1: 13.40 4.04 Reduction was greater in this area in Met individuals compared to GENETICS MEDICAL OF JOURNAL AMERICAN Time 2: 18.31 4.48 Val throughout the time period. Morphometric GM and WM changes in several regions predicted risk for psychotic symptoms (using Leave-out-one Multivariate pattern analysis). In addition to the dPFC, the dorsal cingulum and medial prefrontal cortex were also found to be predictive.
Wang et al. N/A C: 446 (Han Chinese) Age range: 19-21 Both larger hippocampal volumes and better working memory [2013] Subjects with WM task data: GG (WM data; MRI): capabilities were observed in participants with the Val allele. Val GG: 248, GA: 168, AA:27 20.45 0.86; homozygotes performed the best on working memory tasks, Subjects with MRI data: 20.46 0.89 followed by heterozygotes. GG: 173, GA: 128, AA:19 GA (WM data; MRI): 20.32 0.86; 20.34 0.89 AA (WM data; MRI): 20.47 1.0; 20.56 0.92 B PART (Continued) THOMPSON ET AL. 305
regulation of gene expression may act as a buffer for the effects of mutations affecting gene regulation (i.e., mutations in transcrip- tion factors or the sequences of cis-binding sites) in that this RISC system serves to maintain levels of mRNA transcripts within a physiologic range [Brzustowicz and Bassett, 2012]. DGCR8 deficiency in mice has been associated with alterations in the structural morphology of dendritic spines in prefrontal cortex as well as altered prefrontal cortical short-term electrophys- iology and plasticity with impairment in the development of excitatory synapses [Stark et al., 2008; Fenelon et al., 2011; Scho- field et al., 2011; Zhao et al., 2015]. Furthermore, DGCR8 defi- ciency has been linked to a reduction in the elaboration of the dendritic network in the hippocampus [Stark et al., 2008], and has been found to be necessary for neurogenesis in the hippocampi of adult mice [Ouchi et al., 2013]. In mice, DGCR8 was found to regulate 59 miRNAs in prefrontal cortex and 30 in hippocampus [Stark et al., 2008]. DGCR8-/- mice showed downregulation of
volumetric reductions in temporal regionsparahippocampus, (right right hippocampus, fusiform, right bilateral middletemporal gyri), and right superior occipital regions (calcarinea and lingual right regions), parietal regions (precuneus).overlapped The with posterior the cingulate right also parietalsupplementary region. motor Volumetric areas increases and in thewere parietal also and observed occipital in cortices Val homozygotes. 25 mature miRNAs in hippocampus and prefrontal cortex [Zhao Using tensor-based morphometry, Val homozygotes presented with et al., 2015]. These findings suggest that proper miRNA processing is essential to the regulation of genes that are involved in proper prefrontal cortical circuitry development [Schofield et al., 2011; 17.93