Association of serotonin transporter gene polymorphism with obstructive sleep apnea syndrome.

BACKGROUND AND OBJECTIVE: Obstructive sleep apnea syndrome (OSAS) is a common condition characterized by repetitive pharyngeal collapse during sleep and daytime sleepiness. There is genetic predisposition to sleep disorders. Serotonin is involved in the regulation of sleep. The synaptic 5-hydroxytryptamine (HT) is inactivated by presynaptic reuptake, which is mediated by the serotonin transporter. Blockage of the serotonin transporter leads to increased extracellular 5-HT. Polymorphism of the serotonin transporter gene (STG) leads to alterations in serotonin level and may be important in OSAS. In this study, we aimed to assess the role of STG polymorphism in OSAS. METHODS: Twenty-seven OSAS patients and 162 healthy volunteers were involved in the study. STG polymorphism was investigated using leukocytes obtained from peripheral blood. RESULTS: There was no difference between the genotypes and allele frequencies of the patients and controls regarding VNTR and HTTLPR polymorphisms (P > .05). The VNTR and HTTLPR variants and the frequencies of 12/12, 12/10, L, and S alleles were not significantly different between male and female control subjects (P > .05). The 12/12 and SS genotypes were over-represented in the female patients, whereas 12/10 and LL genotypes were over-represented in the male patients (P < .05). The genotypes 12 to 12 were over-represented in the male controls, whereas the genotypes 12 to 10 and L/S were over-represented in the male patients (P < .05). The alleles 10 and L were more frequent in the male patients than male controls (P < .05). The genotypes of female patients and female controls were not significantly different (P > .05). The allele 10 and L were less frequent in the female patients than female controls with Fisher's exact testing (P < .05). There was no relation between genotypes and clinical data of the patients (P > .05). CONCLUSION: STG polymorphism appears to be associated with the occurrence of OSAS, especially in male patients. Absence of association of between genetic variants and polysomnography findings may suggest that some mechanisms other than STG polymorphism are involved in OSAS pathophysiology. Our results need confirmation in a larger group of patients with OSAS.

High frequency of DD polymorphism of the angiotensin-converting enzyme gene in Turkish asthmatic patients.

The aim of this study is to detect the incidence of the angiotensin-converting enzyme (ACE) gene polymorphism in Turkish asthmatic patients and to examine whether there is an association between the disease and ACE gene polymorphism. In our study, the genomic DNA of 100 asthmatic patients and 88 healthy subjects was analyzed Genomic DNA was isolated from peripheral blood by using standard methods. The intron 16 of the ACE gene was amplified by the polymerase chain reaction (PCR) method using primers ACE and ACEX to examine the presence and absence of a 287-base pair (bp) DNA fragment that showed I/D polymorphism genotypes. PCR products were separated by agarose gel electrophoresis and were visualized by a charge-coupled device camera. Serum ACE activities were measured using an ACE kit. The results were evaluated statistically using the chi-square test and one-way analysis of variance. Although the population of patients with asthma was characterized by a higher frequency (30%) of the DD genotype of ACE, they were characterized by lower frequency (48%) of the ID genotype of ACE (DD, 16%, and ID, 64%, in healthy control subjects). The frequency of the I and D alleles of the ACE gene was not significantly different between asthmatic patients (0.46/0.54) and healthy controls (0.52/ 0.48). In addition, in both asthmatic patients and controls, there was a significant decrease of the levels of ACE activity in individuals that have II genotypes when compared with individuals that have DD genotypes. ACE activities were increased significantly in all asthmatic patients (67.20 +/- 1.95 IU/L) compared with all healthy controls (60.90 +/- 2.12 IU/L).