Table 2.

The most important studies investigating genomics of OCD.

Study	Sample size	Population	Genes/SNPs identified	Pathway/pathology
Stewart et al. (45)	1,465 cases, 5,557 ancestry-matched controls and 400 complete trios	European, South African and Ashkenazi Jewish	rs6131295, BTBD3, DHRS11, ISM1, FAIM2, ADCY8, DLGAP1	Cytoskeleton dynamics, ion channel modulation and protein degradation, glutamatergic neurotransmission, post-synaptic density of glutamatergic synapses
Mattheisen et al. (46)	5,061	European	rs4401971, PTPRD, CDH9, IQCK, C16orf88, DLGAP1, GRIK2, NEUROD6, SV2A, GRIA4, SLC1A2	Differentiation of glutamatergic and GABAergic synapses, early neurodevelopment
den Braber et al. (47)	6,931	NR	rs8100480, MEF2BNB, RFXANK, MEF2BNB-MEF2B, MEF2B	Immune system functions, muscle-specific genes' expression
Qin et al. (48)	804	NR	rs17162912, DISP1, rs9303380, rs12437601, rs16988159, rs723815, rs7676822, rs1911877, GRIN2B, PCDH10, GPC6	Glutamatergic and serotonergic neurotransmission
Umehara et al. (49)	96	Asian (Japanese)	CHN2	Calcium signaling
Guo et al. (50)	9,896	European	rs4785741, MC1R, TUBB3, DDAH1, IMPA2, PTH2R	Hair color, pigmentation, neurogenesis, CVDs, susceptibility to bipolar disorder, PTH
IOCDF-GC and OCGAS (13)	9,725	European	rs4733767, CASC8/CASC11, rs1030757, GRID2, rs12504244, KIT, ASB13, RSPO4, DLGAP1, PTPRD, GRIK2, FAIM2, CDH20	Glutamatergic neurotransmission
Khramtsova et al. (51)	9,870	European	GRID2, GPR135	Glutamatergic signaling system
Cross-Disorder Group of the Psychiatric Genomics Consortium (2019) (52)	727,126	European	109 pleiotropic loci	Neurodevelopment
Alemany-Navarro et al. (53)	399	European	SETD3, CPE	Zinc ion response and lipid metabolism, lipid metabolism, G protein-mediated processes, metabolic processes, and anion transport
Costas et al. (54)	813	European	DNM3	Endocytosis of synaptic vesicles
Smit et al. (55)	8,267	European	KIT, GRID2, WDR7, ADCK1	Emotional, reward processing, memory, fear-formation functions
Burton et al. (56)	5,018	European	rs7856850 (PTPRD)	Differentiation of neurons
Strom et al. (57)	390,290	European	PRS of neuroticism, bipolar disorder, anorexia nervosa, age at first birth, educational attainment, and insomnia	Neuroticism, bipolar disorder, anorexia nervosa, age at first birth, educational attainment, and insomnia

Studies are listed in chronological order. SETD3, SET domain containing 3 gene; PTPRD, protein tyrosine phosphatase δ gene; CPE, carboxypeptidase E gene; DNM3, dynamin 3 gene; MEF2BNB, myocyte enhancer binding factor 2B gene; RFXANK, DNA-binding protein RFXANK gene; MC1R, melanocortin 1 receptor gene; TUBB3, tubulin beta 3 gene; DDAH1, dimethylarginine dimethylaminohydrolase 1 gene; IMPA2, inositol monophosphatase 2 gene; PTH2R, parathyroid hormone 2 receptor; CASC8/CASC11, cancer susceptibility 8 and cancer susceptibility 11 genes; GRID2, glutamate ionotropic receptor delta type subunit 2 gene; KIT, proto-oncogene, receptor tyrosine kinase gene; ASB13, ankyrin repeat and SOCS box containing 13 gene; RSPO4, R-spondin 4 gene; DLGAP1 gene, discs large homolog associated protein 1; FAIM2, fas apoptotic inhibitory molecule 2 gene; CDH20, cadherin 20 gene; GPR135, G protein-coupled receptor 135 gene; CDH9, cadherin 9 gene; IQCK, IQ motif containing K gene; NEUROD6, neuronal differentiation 6 gene; SV2A, synaptic vesicle glycoprotein 2A gene; GRIA4, glutamate ionotropic receptor AMPA type subunit 4 gene; SLC1A2, solute carrier family 1 member 2 gene; WDR7, WD repeat-containing protein 7 gene; ADCK1, AarF domain-containing protein kinase 1 gene; BTBD3, BTB domain-containing 3 gene; DHRS11, dehydrogenase/reductase 11 gene; ISM1, isthmin 1 gene; ADCY8, adenylate cyclase type 8 gene; DISP1, dispatched RND transporter family member 1 gene; GRIN2B, glutamate ionotropic receptor NMDA type subunit 2B gene; PCDH10, protocadherin 10 gene, GPC6, glypican 6 gene, CHN2, chimerin 2 gene; LRRC16A, leucine-rich repeat-containing 16A gene; PRS, polygenic risk score.