Abstract

Introduction/Review: Although individuals with schizophrenia have a markedly higher than average rate of tobacco smoking, multiple studies have shown that their risk of lung cancer is lower than that of the general population [1-3]. There are both environmental and genetic factors that form possible explanations for the protective link between these two conditions. This study aims to shed light on the genetic aspect of this relationship.

Methodology: Two unique search queries were run through OMIM (Online Mendelian Inheritance in Man) to obtain the known genetic links of both schizophrenia and lung cancer. These results were then crossmatched. One of the common genes, the SLC6A3 gene, was selected for further research. Multiple electronic databases were then searched with results going back over the past 37 years (1981 through 2018). Per our inclusion criteria, the abstract sections as well as the titles were sorted independently by two authors. Articles were sorted into relevant and irrelevant categories, with irrelevant articles being discarded. The full text was obtained for articles deemed to be relevant and were then reviewed by both authors.

Result: One study proved a positive correlation between the DAT1 A/T polymorphism and schizophrenia among a population of Iranian males [4]. Evidence from various studies suggests that dopamine possesses tumor inhibiting effects [5-8]. The expression of DAT1 was found in both the brain and the lungs [9-11].

Conclusion: The SLC6A3 encoded DAT1 may be the source of the protective effect against lung cancer that patients with schizophrenia appear to possess. Although preliminary findings have been positive, additional high-quality research in the area of study will be needed to further delineate the relationship between the two.

Keywords: Schizophrenia; Dopamine; Lung cancer; DAT1; Dopamine Transporter gene; Cigarette smoking

Abbreviation: DAT1: Dopamine Transporter1; VPF/VEGF: Vascular Permeability Factor/ Vascular Endothelial Growth Factor; D2R: Dopamine D2 Receptor; HUVEC: Human Umbilical Vein Endothelial Cell