A Systematic Analysis of Candidate Genes Associated with Nicotine Addiction

Table 1

Gene clusters identified in the nicotine addiction-related network.

Cluster	Cluster function	Score^a	Nodes	Edges	Gene symbol
I	Apoptotic/macromolecular; metabolic process	4.08	25	49	ARRB2, ARRB1, CUL4A, HDAC1, RPS3, ERCC6, GNAS, UBE3A, NBN, CHEK2, BRCA1, ESR1, ARR3, AR, HDAC2, NEDD4, UBB, MSH6, NR3C1, UBC, PDE4D, SUMO1, HIF1A, TUBB2A, ITCH
II	Synaptic transmission/intracellular and second messenger signaling cascade	2.67	13	16	KCNJ9, DRD2, ADRB2, DRD4, NOS3, MAP1A, GCDH, TTN, HTR2A, PSEN1, ACTN1, KCNJ3, GNA11
III	Behavioral response to nicotine	3.00	3	3	UBQLN1, CHRNB4, CHRNA3
IV	Response to abiotic stimulus/cellular; metabolic process	3.05	22	32	BRCA2, GAPDH, H2AFX, SPTAN1, PRMT1, PRKG1, MGMT, NCL, HECW2, USP11, ATR, LMNA, GRIN2A, CDK5, TP53, GRIN2B, KPNB1, XRCC6, MRE11A, TCEAL1, PLCG1, PDCD5
V	Cellular response to DNA damage stimulus/DNA metabolic process	3.29	15	23	RPA2, RPA3, CCNH, HSPA4, ERCC3, XRCC1, RPA1, GTF2H1, MLH1, PCNA, MYC, XPC, ATM, CDK2, SUMO2
VI	Synaptic transmission/cell-cell signaling	3.00	3	3	NSF, GABBR1, GABBR2

Score is defined as the product of the cluster density and the number of vertices (proteins) in the cluster ().