Table 3 Weights for genes in two pathways that show an association with smoking status. SVD weights for genes in pathways identified as significantly differentially expressed between current and never smokers. The gene with highest absolute weight in the gamma-Hexachlorocyclohexane degradation pathway, CYP2A6, plays a key role in nicotine metabolism and has been linked to nicotine dependence [21]. GALNT3, a gene with relatively high weight in the O-Glycans biosynthesis pathway, initiates mucin-type O-glycosylation [22], suggesting a connection with the increased sputum production observed in smokers. The overall sign of the weights has here been chosen so that a positive weight implies relatively higher expression in current as compared to never smokers.

From: Pathway level analysis of gene expression using singular value decomposition