The Association of Brain-Derived Neurotrophic Factor Gene Polymorphism with Obstructive Sleep Apnea Syndrome and Obesity.

Background: Obesity represents a major risk factor for Obstructive Sleep Apnea Syndrome (OSAS). Brain-derived neurotrophic factor (BDNF) affects the mechanisms that regulate weight, eating behavior, and metabolism. This project aims to investigate the possible association of BDNF gene polymorphism with obesity and OSAS, and to contribute knowledge to the understanding of the pathophysiology of OSAS.

Methods: The subjects included in this study were selected among the individuals who were hospitalized in the Erciyes University Medical School Chest Diseases Sleep Medicine Laboratory. Subjects were divided into four groups based on the presence of OSAS and/or obesity. Group 1 included OSAS+ obesity+ patients, Group 2 included OSAS+ obesity- patients, Group 3 included OSAS- obesity+ patients, and Group 4 included OSAS- obesity- patients. The targeted patient number per each study group was 45, but only 32 patients could be enrolled into Group 3.

Results: Out of a total number of 167 subjects, 117 (70.1 %) had BDNF 196G/G, 48 (28.7 %) had BDNF 196G/A, and 2 (1.2 %) had BDNF 196A/A genotype. Of 48 subjects having BDNF 196G/A genotype, 32 (66.6 %) were obese, and 16 (33.3 %) were non-obese. Out of 90 subjects with OSAS, 64 (71.1 %) had BDNF 196G/G, and 25 (27.8 %) had BDNF 196G/A genotype. Out of 77 subjects without OSAS, BDNF 196G/G, and BDNF 196G/A genotypes were detected in 53 (68.8 %) and 23 (29.9 %) subjects, respectively. A statistically significant difference was demonstrated between the four study groups in terms of BDNF rs6265 polymorphism (p = 0.013). This difference was attributed to OSAS+ obesity- Group, in which BDNF 196G/G genotype was more common and BDNF 196G/A polymorphism was less common than the patients in other groups.

Conclusion: In conclusion, BDNF 196G/A genotype was found to be more frequent among obese patients compared to the non-obese individuals, but it was not significantly related to OSAS in the present study. BDNF196G/G genotype was more common and BDNF 196G/A polymorphism was less common among OSAS+ obesity- subjects compared to the other study groups.