GENETICS OF LONG-TERM TREATMENT
OUTCOME IN BIPOLAR DISORDER
Alessandro Serretti, Chiara Fabbri
Department of Biomedical and NeuroMotor
Sciences, University of Bologna, Italy
Dr. Serretti is or has been consultant/speaker for: Abbott, Astra Zeneca, Clinical Data,
Bristol Myers Squibb, Boheringer, Eli Lilly, GlaxoSmithKline, Janssen, Lundbeck, Pfizer,
Sanofi, Servier
Background
 BP shows one of highest genetic predisposition among
psychiatric disorders (heritability index: 0.85) (McGuffin et al. 2003)
Genetics accounts for 20% to 95% of variability in CNS
drug disposition and pharmacodynamics (Cacabelos et al. 2012)
Much treatment failure and non-adherence (from 12% to
64%) would be improved thanks to genetic predictors of
treatment response
Background
 Previous pharmacogenetic studies were mainly focused on
lithium response
Candidate gene studies were focused on: monoaminergic
system (SLC6A4 and genes coding for dopaminergic
receptors), intracellular second messengers (INPP1, GSK3β,
and CREB1), and neurotrophin system (BDNF)
Overlap of lithium-responsive genes and treatment response-associated SNPs
Neuronal
cell
adhesion
molecules
Cell cycle regulators
Signal transduction
Transcription factor
Ionotropic
glutamate
receptor
Genetics of lithium response
Hazard of
recurrence of an
acute episode of
any polarity
One of the best
findings was on 4q32
(intergenic)
The region includes ACCN5
(amiloride-sensitive sodium channel,
may play a role in neurotransmission)
and GRIA2
STEP-BD study
(Systematic Treatment Enhancement ProgramBipolar Disorder)
Multi-center, longitudinal (5-8 year) NIMH project
 Naturalistic design
 Basic clinical research need: test treatments with
demonstrable efficacy in double-blind trials in open
clinical practice
 Bipolar I, Bipolar II, Cyclothymia, Bipolar NOS, or
Schizoaffective Manic or Bipolar subtypes

Present Aim
 Identify
genes associated with long-term
treatment efficacy (more than 6 months) in
the STEP-BD genome-wide study,
including all treatment regimens in order to
reflect a real clinical practice scenario
Phenotypes
I.
Total recurrence rate: total number of episodes / total
number of visits ratio
II.
Depressive recurrence rate: number of depressive episodes /
total number of visits ratio
III.
Occurrence of at least one hypomanic, manic or mixed
episode during follow-up
Statistical analysis

Quality control: HWE p>0.001, MAF>0.05, total
genotyping rate>95%, individual genotyping rate
>90%
 Identity-by-descent
(IBD) analysis was used to
identify related subjects (IBD > 0.1875, Anderson et al.
2010)
 Ancestry clusters were defined on the base of the
pairwise population concordance test (PCC <
0.0001, Purcell et al. 2007)

Linear or logistic regression models as appropriate
Statistical analysis
 Covariates:
age, gender, ancestry, monotherapy
vs. polytherapy.
 Pathway functional enrichment: genes containing
SNPs with p<10e-4 were analyzed through the
GeneMANIA plugin (www.genemania.org/) in
Cytoscape (www.cytoscape.org/).
 Pathway analysis: GO terms with FDR < 0.05
were analyzed for a different distribution of SNPs
with p<0.05 and p<0.01 compared to a random
matched pathway (Fisher exact test) after the
imputation of the included genes. 10e04
permutations were run.
Results – Sample
Variable
Gender F/M
Age
Diagnosis
Ethnicity
Description
398/325
41.47±12.48
BP I (all)
White or Caucasian (all)
Age at first manic episode
21.89±11.50
N of previous (hypo) manic
episodes
Too many to count: 117
20 – 50: 90
10 – 20: 110
5 – 9: 103
3 – 4: 111
1-2: 114
0: 6
NA: 72
Age at first depressive
episode
17.29±11.38
Results – Sample
Variable
N of previous depressive
episodes
Follow-up duration (days)
N of visits
N of total episodes
Description
Too many to count: 159
20 – 50: 99
10 – 20: 124
5 – 9: 87
3 – 4: 88
1-2: 74
0: 20
NA: 72
840.34±412.39
21.62±14.21
5.04±6.78
N of depressive episodes
3.82±5.85
N of (hypo)manic/mixed
episodes
1.22±2.27
Monotherapy/polytherapy
179/ 544
Results – Sample
Variable
Litium yes/no
Valproate yes/no
Other mood stabilizers yes/no
Second generation
Antipsychotics yes/no
First generation
antipsychotics yes/no
Description
299/424
226/497
365/358
357/366
SSRIs yes/no
130/593
SNRIs yes/no
40/683
Other antidepressants yes/no
135/588
11/712
Results – total recurrence
Results – depressive recurrence
Results – other suggestive signals
Total recurrence
Gene
SNP
Beta
Stat
p
SORCS2
rs16840900
0.09
4.66
3.94e-06
NRXN1
rs10187465
-0.06
-4.46
9.99e-06
(hypo)manic recurrence -> no significant finding
Results – functional enrichment
Total recurrence
GO ID
Description
FDR
Observed genes
GO:0007610
Behavior
3.41e-08
ZIC1, USP46, TAS2R1, SHANK1, RASGRF1,
PLK2, PLCB1, NTRK2, LRRK2, JAM3, GRIN2B,
GRIN2A, FYN, F3, EFNB2, DLG4, CNTNAP2,
CDH13, CAMK1D
GO:0007611
Learning and
memory
1.42e-05
SHANK1, RASGRF1, PLK2, PLCB1, NTRK2,
GRIN2B, GRIN2A, FYN, DLG4
GO:0050890
Cognition
9.96e-05
SHANK1, RASGRF1, PLK2, PLCB1, NTRK2,
GRIN2B, GRIN2A, FYN, DLG4
GO:0021537
Telencephalon
development
0.01
SALL1, PLCB1, NTRK2, LRRK2, LEF1, EPHB2,
CNTNAP2
GO:0007420
Brain
development
0.04
ZIC1, SALL1, PLCB1, PCDH18, NTRK2, LRRK2,
LEF1, FOXA2, EPHB2, CTNNA2, CNTNAP2
Results – functional enrichment
Depressive recurrence
GO ID
Description
FDR
Observed genes
GO:0043410
Positive
2.28e-04 TGFB2, SDCBP, PDGFRA, NTF3, MAP2K6,
regulation of
LRRK2, KIT, GRM4, CHRNA7, ARRB1
MAPK cascade
GO:0007610
Behavior
6.59e-04 PLK2, PDGFRA, NTF3, LRRK2, FYN, F7, F3,
CNTNAP2, CHRNA7
GO:0032147
Activation of
protein kinase
activity
0.003
TGFB2, NTF3, MAP3K1, MAP2K6, LRRK2, KIT,
GRM4, CHRNA7
GO:0043005
Neuron
projection
0.003
TGFB2, PLK2, MAGI2, LRRK2, KIF1B, GRM7,
EPHA4, CNTNAP2
GO:0022604
Regulation of
cell
morphogenesis
0.003
TGFB2, PTPRD, LRRK2, LEF1, KIT, FOXA2,
EPHA4, CAPZB
GO:0060326
Cell
chemotaxis
0.003
TGFB2, PDGFRA, LEF1, KIT, F7, CCR6, CCL20
Results – functional enrichment
Depressive recurrence
GO ID
Description
FDR
Observed genes
GO:0048863
Stem cell
differentiation
0.004 TGFBR3, TGFB2, PDGFRA, LEF1, KIT, FOXA2,
CTR9
GO:0030425
Dendrite
0.004 PLK2, MAGI2, LRRK2, GRM7, EPHA4,
CNTNAP2
GO:0032970
Regulation of actin 0.004 PPFIA1, PDGFRA, PDE4D, NTF3, MTPN, KCNJ2,
filament-based
HAX1
process
GO:0097458
Neuron part
0.01
TGFB2, PLK2, MAGI2, LRRK2, KIF1B, GRM7,
EPHA4, CNTNAP2
GO:0010769
Regulation of cell
morphogenesis
involved in
differentiation
0.01
TGFB2, PTPRD, LRRK2, LEF1, FOXA2, EPHA4
GO:0048864
Stem cell
development
0.02
TGFBR3, TGFB2, LEF1, KIT, CTR9
Results – functional enrichment
Depressive recurrence
GO ID
Description
FDR
Observed genes
GO:0044708
Single-organism
behavior
0.02
PLK2, LRRK2, FYN, CNTNAP2, CHRNA7
GO:0031623
Receptor
internalization
0.02
NTF3, MAGI2, DNM2, ARRB1
GO:0071902
Positive regulation 0.03
of protein
serine/threonine
kinase activity
NTF3, MAP2K6, LRRK2, KIT, GRM4, CHRNA7
GO:0007611
Learning and
memory
PLK2, FYN, CNTNAP2, CHRNA7
GO:0008066
Glutamate receptor 0.03
activity
GRM7, GRM4, GRM3
GO:0030335
Positive regulation 0.03
of cell migration
TGFB2, PDGFRA, NTF3, LEF1, F7, F3
0.03
Results – pathway analysis
Total recurrence – Learning and memory
For p<0.05:
p=0.09,
OR=0.48
(0.20-1.10)
For p<0.01:
p=0.07,
OR=0.14
(0.003-1.10)
11% SNPs with
p<0.05
7% SNPs with
p<0.05
8% SNPs with
p<0.05
15% SNPs with
p<0.05
Results – pathway analysis
Depressive recurrence – positive regulation of MAPK cascade
20% SNPs with
p<0.05
55% SNPs with
p<0.05
GRM4
20% SNPs with
p<0.05
For p<0.05:
p=0.0006,
OR=0.06
(0.001- 0.42)
Perm. p=0.55
For p<0.01:
p=0.06,
OR=0.13
(0.003-1.08)
Discussion – Top genes
 TRAF3IP2-AS1: structural RNA gene at 6q21 associated
with schizophrenia by linkage studies (Cao et al., 1997; Morelli et al,
2000)
SORCS2 and NRXN1: both associated with BP by GWAS
(Baum et al., 2008a; O'Dushlaine et al., 2011) and candidate gene studies (Ollila
et al., 2009; Takata et al., 2011); NRXN1 associated with antidepressant
response (Tansey et al., 2014) and antipsychotic response (Jenkins et al.,
2014)
DFNB31: bipolar linkage region (Mburu et al., 2003); BP
susceptibility according to GWAS (Baum et al., 2008a; Baum et al., 2008b)
and a candidate gene study (Ollila et al., 2009); involved in GSK3β
pathway that is a target of Li+
Discussion – DFNB31 gene
Depressive and total recurrence
Mol Psychiatry. 2008;
13(2):197-207.
Discussion – DEPTOR gene
Depressive and total recurrence
DEPTOR: part of the
mammalian target of rapamycin
complex 1 (mTORC1) that is
involved in SSRI and especially
ketamine antidepressant effect
(Abelaira et al, 2014; Park et al., 2014)
Life Sci.
2014;
Mol Psychiatry.
2008;
101:10-4
13(2):197-207.
Discussion – Top genes
NFYC: involved in the control of cell cycle blocks and
signaling pathways, possibly in synaptic plasticity (Mitlon et al.,
2013)
RNLS: FAD-dependent amine oxidase that is involved in
the degradation of catecholamines, unknown any possible
correlation with BP
rs41368245 and near SNPs, 700 Kbp from KCNJ2
(17q24.3): inward rectifier potassium channel, potassium
channels are involved in treatment response in BP and
considered attractive targets for novel therapeutics for BP (Judy
et al., 2013)
Discussion – Top genes from pathway
analysis
Cell adhesion molecules (JAM3, CNTNAP2, PTPRD) that
have been implicated in BP (O'Dushlaine et al., 2011)
 Molecules involved in synaptic plasticity and/or neuron
survival (NTRK2 [BDNF receptor], NTF3, RASGRF1,
CHRNA7)
Glutamate receptors (GRIN2B, GRIN2A, GRM4)
implicated in BP (Fallin et al., 2005; Cherlyn et al., 2010) and mood
stabilizer action (protection against glutamate excitotoxicity,
Hashimoto et al., 2002)
Limitations
No selection of patients on the basis of treatment/treatment
class, resulting in potential bias due to stratification, but
design more adherent to the real clinical practice
 Given study methods, findings may represent genetic
markers of disease course/severity rather than markers of
treatment response
Follow-up duration lacked of standardization and widely
varied among included patients
Conclusion
Genes previously involved in the susceptibility to BP
(DFNB31, SORCS2, NRXN1, CNTNAP2, GRIN2A, GRM4,
GRIN2B), antidepressant action (DEPTOR, CHRNA7,
NRXN1) and mood stabilizer or antipsychotic action
(NTRK2, CHRNA7, NRXN1) may affect long-term
treatment outcome of BP under naturalistic treatment.
Unit of Mood Disorders, Institute of Psychiatry,
University of Bologna, Italy
Stefano Porcelli MD
Alessandro Serretti MD PhD
Elena Toscano MD
Yoshiteru Takekita MD PhD
Laura Mandelli PsyD, PhD
Martina Balestri MD
Chiara Fabbri MD
Agnese Marsano MD
Rosalba Martines, BS