CHRNA4 and nicotine dependence: Similar to the study in Japan (Chen et al., 2013), an early study with male Chinese smokers revealed that the CHRNA4 risk polymorphism (rs1044396) was significantly associated with age at smoking initiation and the CHRNA4 risk polymorphisms (rs1044396 and rs1044397) were associated with nicotine dependence (Chu et al., 2011).