LAUSR

Objectives: Surfactant protein D (SP-D) are clinically established as potential serum biomarkers for in Chinese male patients with obstructive sleep apnea hypopnea syndrome (OSAHS). Serum SP-D levels are affected by genetic variants. This case-control study was conducted to explore the association between genetic variations in SP-D gene and OSAHS. Methods: 169 severe OSAHS patients and 176 patients without OSAHS were consecutively enrolled from Hypertension Center of People's Hospital of Xinjiang Uygur Autonmous Region. Circulating SP-D in the serum were measured using an enzyme-linked immunosorbent assay, and two single-nucleotide polymorphisms (SNPs) in the SFTPD gene (rs721917 and rs2243639) were genotyped by KASP using genomic DNA extracted from blood samples. Results: (1) Patients with severe OSAHS showed significantly lower concentration of serum SP-D (P = 0.032) compared with those in controls. (2) The distributions of genotypes and alleles of rs721917 showed significant differences between controls and severe-OSAHS (P < 0.05) in total and subjects with BMI≥24 (P < 0.05), as well as genotypes of rs2243639 in subjects with BMI≥24 (P < 0.05). (3) Furthermore, logistic regression analysis revealed that the CT and TT genotype of rs721917 were protective factors for severe-OSAHS patients, adjusting for sex, BMI, cigarette smoking and alcohol consumption [TT: OR (95% CI): 0.3 (0.131–0.840), P = 0.020; CT: OR (95%CI): 0.214 (0.105–0.433), P < 0.001]. (4) Patients with TT + TC genotypes displayed significant higher AHI, HI and AI compared with patients with CC genotypes (P < 0.05). Conclusion: Serum SP-D concentration were significantly lower in patients with severe OSAHS than in the patients without OSAHS, partly because of the different distributions of genotypes and alleles of rs721917 in SFTPD gene.