Chronic non-transmittable diseases such as obesity and cancer are complex diseases, which involve multiple genetic and environmental factors as well as complicated interactions among those factors. Previously, JMCB published several issues exploring complex diseases from various perspectives (Chen and Wu, 2012; Wu, 2012, 2013, 2016). Research articles in the current issue report molecular factors or mechanisms that were recently found to be involved in various complex diseases, which might provide new candidates for biomarkers or drug targets against these complex diseases.