A genome-wide association study based on the China Kadoorie Biobank identifies genetic associations between snoring and cardiometabolic traits

Despite the high prevalence of snoring in Asia, little is known about the genetic etiology of snoring and its causal relationships with cardiometabolic traits. Based on 100,626 Chinese individuals, a genome-wide association study on snoring was conducted. Four novel loci were identified for snoring traits mapped on SLC25A21, the intergenic region of WDR11 and FGFR, NAA25, ALDH2, and VTI1A, respectively. The novel loci highlighted the roles of structural abnormality of the upper airway and craniofacial region and dysfunction of metabolic and transport systems in the development of snoring. In the two-sample bi-directional Mendelian randomization analysis, higher body mass index, weight, and elevated blood pressure were causal for snoring, and a reverse causal effect was observed between snoring and diastolic blood pressure. Altogether, our results revealed the possible etiology of snoring in China and indicated that managing cardiometabolic health was essential to snoring prevention, and hypertension should be considered among snorers.

Snoring-related polygenic risk and its relationship with lifestyle factors in a Korean population: KoGES study

Whereas lifestyle-related factors are recognized as snoring risk factors, the role of genetics in snoring remains uncertain. One way to measure the impact of genetic risk is through the use of a polygenic risk score (PRS). In this study, we aimed to investigate whether genetics plays a role in snoring after adjusting for lifestyle factors. Since the effect of polygenic risks may differ across ethnic groups, we calculated the PRS for snoring from the UK Biobank and applied it to a Korean cohort. We sought to evaluate the reproducibility of the UK Biobank PRS for snoring in the Korean cohort and to investigate the interaction of lifestyle factors and genetic risk on snoring in the Korean population. In this study, we utilized a Korean cohort obtained from the Korean Genome Epidemiology Study (KoGES). We computed the snoring PRS for the Korean cohort based on the UK Biobank PRS. We investigated the relationship between polygenic risks and snoring while controlling for lifestyle factors, including sex, age, body mass index (BMI), alcohol consumption, smoking, physical activity, and sleep time. Additionally, we analyzed the interaction of each lifestyle factor and the genetic odds of snoring. We included 3526 snorers and 1939 nonsnorers from the KoGES cohort and found that the PRS, a polygenic risk factor, was an independent factor for snoring after adjusting for lifestyle factors. In addition, among lifestyle factors, higher BMI, male sex, and older age were the strongest lifestyle factors for snoring. In addition, the highest adjusted odds ratio for snoring was higher BMI (OR 1.98, 95% CI 1.76-2.23), followed by male sex (OR 1.54, 95% CI 1.28-1.86), older age (OR 1.23, 95% CI 1.03-1.35), polygenic risks such as higher PRS (OR 1.18, 95% CI 1.08-1.29), drinking behavior (OR 1.18, 95% CI 1.03-1.35), late sleep mid-time (OR 1.17, 95% CI 1.02-1.33), smoking behavior (OR 0.99, 95% CI 0.82-1.19), and lower physical activity (OR 0.92, 95% CI 0.85-1.00). Our study identified that the UK Biobank PRS for snoring was reproducible in the Korean cohort and that genetic risk served as an independent risk factor for snoring in the Korean population. These findings may help to develop personalized approaches to reduce snoring in individuals with high genetic risk.

Association Between Sleep Traits and Rheumatoid Arthritis: A Mendelian Randomization Study

Currently, the causal association between sleep disorders and rheumatoid arthritis (RA) has been poorly understood. In this two-sample Mendelian randomization (TSMR) study, we tried to explore whether sleep disorders are causally associated with RA. Seven sleep-related traits were chosen from the published Genome-Wide Association Study (GWAS): short sleep duration, frequent insomnia, any insomnia, sleep duration, getting up, morningness (early-to-bed/up habit), and snoring, 27, 53, 57, 57, 70, 274, and 42 individual single-nucleotide polymorphisms (SNPs) (P < 5 × 10-8) were obtained as instrumental variables (IVs) for these sleep-related traits. Outcome variables were obtained from a public GWAS study that included 14,361 cases and 43,923 European Ancestry controls. The causal relationship between sleep disturbances and RA risk were evaluated by a two-sample Mendelian randomization (MR) analysis using inverse variance weighted (IVW), MR-Egger regression, weighted median, and weight mode methods. MR-Egger Regression and Mendelian randomization pleiotropy residual sum and outlier (MR-PRESSO) were used to test for horizontal pleomorphism and outliers. There was no evidence of a link between RA and frequent insomnia (IVW, odds ratio (OR): 0.99; 95% interval (CI): 0.84-1.16; P = 0.858), any insomnia (IVW, OR: 1.09; 95% CI: 0.85-1.42; P = 0.489), sleep duration (IVW, OR: 0.65, 95% CI: 0.38-1.10, P = 0.269), getting up (IVW, OR: 0.56, 95% CI: 0.13-2.46, P = 0.442), morningness (IVW, OR: 2.59; 95% CI: 0.73-9.16; P = 0.142), or snoring (IVW, OR: 0.95; 95% CI: 0.68-1.33; P = 0.757). Short sleep duration (6h) had a causal effect on RA, as supported by IVW and weighted median (OR: 1.47, 95% CI: 1.12-1.94, P = 0.006; OR: 1.43, 95%CI:1.01-2.05, P = 0.047). Sensitivity analysis showed that the results were stable. Our findings imply that short sleep duration is causally linked to an increased risk of RA. Therefore, sleep length should be considered in disease models, and physicians should advise people to avoid short sleep duration practices to lower the risk of RA.

Genetic Evidence Supporting a Causal Role of Snoring in Erectile Dysfunction

Background

The association between snoring and erectile dysfunction (ED) is inconsistent in multiple observational studies. To clarify the causal association of snoring on ED, we performed this two-sample Mendelian randomization study.

Materials and Methods

The single nucleotide polymorphisms (SNPs) associated with snoring were retrieved from the UK biobank cohort with 314,449 participants (117,812 cases and 196,637 controls). The summary statistics of ED were obtained from the European ancestry with 223,805 subjects (6,175 cases and 217,630 controls). Single-variable Mendelian randomization (MR) and multivariable MR were used to assess the causal relationship between snoring and ED.

Results

Snoring increases the risk of ED (Odds ratio [OR] = 3.45, 95% confidence interval [CI] = 1.68 - 7.09, P < 0.001) in the inverse variance weighting estimator. In sensitivity analyses, the ORs for the weighted median, MR robust adjusted profile score, and MR Pleiotropy Residual Sum and Outlier approach, MR-Egger, and maximum likelihood method are 5.70 (95% CI = 1.19 - 27.21, P < 0.05), 3.14 (95% CI = 1.01 - 9.72, P < 0.05), 3.11 (95% CI = 1.63 - 5.91, P < 0.01), 1.23 (95% CI = 0.01 - 679.73, P > 0.05), and 3.59 (95% CI = 1.07 - 12.00, P < 0.05), respectively. No heterogeneity and pleiotropy are observed (P for MR-Egger intercept = 0.748; P for global test = 0.997; P for Cochran's Q statistics > 0.05). After adjusting for total cholesterol, triglyceride, low-density lipoprotein, and cigarette consumption, the ORs for ED are 5.75 (95% CI = 1.80 - 18.34, P < 0.01), 4.16 (95% CI = 1.10 - 15.81, P < 0.05), 5.50 (95% CI = 1.62 - 18.69, P < 0.01), and 2.74 (95% CI = 1.06 - 7.10, P < 0.05), respectively.

Conclusion

This study provides genetic evidence supporting the causal role of snoring in ED.

miR-21-5p Under-Expression in Patients with Obstructive Sleep Apnea Modulates Intermittent Hypoxia with Re-Oxygenation-Induced-Cell Apoptosis and Cytotoxicity by Targeting Pro-Inflammatory TNF-α-TLR4 Signaling

The purpose of this study is to explore the anti-inflammatory role of microRNAs (miR)-21 and miR-23 targeting the TLR/TNF-α pathway in response to chronic intermittent hypoxia with re-oxygenation (IHR) injury in patients with obstructive sleep apnea (OSA). Gene expression levels of the miR-21/23a, and their predicted target genes were assessed in peripheral blood mononuclear cells from 40 treatment-naive severe OSA patients, and 20 matched subjects with primary snoring (PS). Human monocytic THP-1 cell lines were induced to undergo apoptosis under IHR exposures, and transfected with miR-21-5p mimic. Both miR-21-5p and miR-23-3p gene expressions were decreased in OSA patients as compared with that in PS subjects, while TNF-α gene expression was increased. Both miR-21-5p and miR-23-3p gene expressions were negatively correlated with apnea hypopnea index and oxygen desaturation index, while TNF-α gene expression positively correlated with apnea hypopnea index. In vitro IHR treatment resulted in decreased miR-21-5p and miR-23-3p expressions. Apoptosis, cytotoxicity, and gene expressions of their predicted target genes—including TNF-α, ELF2, NFAT5, HIF-2α, IL6, IL6R, EDNRB, and TLR4—were all increased in response to IHR, while all were reversed with miR-21-5p mimic transfection under IHR condition. The findings provide biological insight into mechanisms by which IHR-suppressed miRs protect cell apoptosis via inhibit inflammation, and indicate that over-expression of the miR-21-5p may be a new therapy for OSA.

Unexpected Finding of Idiopathic REM Sleep Behavior Disorder in a Young Healthy Male With Snoring: A Case Report

None

Idiopathic rapid eye movement sleep behavior disorder is characterized by vocalizations and complex motor behaviors during sleep. We report a case of a 44-year-old male with a 20-year history of dream enactment behavior that was incidentally captured on a polysomnogram during an evaluation for obstructive sleep apnea. Genetic testing found the patient had a homozygous deletion for one of the five tandem repeats in exon 18 of the PER3 gene. This case highlights a potential genetic basis for idiopathic rapid eye movement sleep behavior disorder.

CITATION

Brock MS, Shirley S, Rohena L, Moore BA, Mysliwiec V. Unexpected finding of idiopathic REM sleep behavior disorder in a young healthy male with snoring: a case report. J Clin Sleep Med. 2019;15(9):1369-1371.

Obstructive sleep apnea and rhonchopathy are associated with downregulation of trefoil factor family peptide 3 (TFF3)-Implications of changes in oral mucus composition

Study objectives

Trefoil factor family (TFF) peptides belong to the family of mucin-associated peptides and are expressed in most mucosal surfaces. TFF peptides carry out functions such as proliferation and migration enhancement, anti-apoptosis, and wound healing. Moreover, TFFs are associated with mucins and interact with them as “linker peptides”, thereby influencing mucus viscosity.

To test the hypothesis that in rhonchopathy and obstructive sleep apnea (OSA) changes occur in the expression of TFF3 and -2 that could contribute to changes in mucus viscosity, leading to an increase in upper airway resistance during breathing.

Methods

RT-PCR, Western-blot, immunohistochemistry and ELISA were performed to detect and quantify TFF3 and -2 in uvula samples. In addition, 99 saliva samples from patients with mild, moderate or severe OSA, as well as samples from rhonchopathy patients and from healthy volunteers, were analyzed by ELISA.

Results

TFF3 was detected in all uvula samples. Immunohistochemistry revealed a subjectively decreasing antibody reactivity of the uvula epithelia with increasing disease severity. ELISA demonstrated significantly higher TFF3 saliva protein concentrations in the healthy control group compared to cases with rhonchopathy and OSA. Predisposing factors of OSA such as BMI or age showed no correlation with TFF3. No significant changes were observed with regard to TFF2.

Conclusions

The results suggest the involvement of TFF3 in the pathogenesis of rhonchopathy and OSA and lead to the hypothesis that reduction of TFF3 production by the epithelium and subepithelial mucous glands of the uvula contribute to an increase in breathing resistance due to a change in mucus organization.

Examining the association between Apolipoprotein E (APOE) and self-reported sleep disturbances in non-demented older adults

We aimed to examine the association between Apolipoprotein E (APOE) and sleep disturbances. This is a cross-sectional study, from the Washington Heights-Inwood Community Aging Project (WHICAP). A total of 1944 non-demented older adults took part in the study. Sleep dysfunction was measured using sleep categories derived from the Medical Outcomes Study Sleep Scale. Genetic association between APOE-ϵ4 genotype and sleep disturbances was assessed using unadjusted linear regression models. Secondary analyses were conducted adjusting for age, sex, education, ethnicity and body mass index (BMI). In the unadjusted model, individuals carrying the APOE-ϵ4 allele showed lower levels of snoring (β=-0.02, SE=0.01, p=0.010) and sleep apnea (β=-0.01, SE=0.01, p=0.037) when compared to non-ϵ4 carriers. After covariates' adjustment, ϵ4 carriers demonstrated stronger association with lower levels of both snoring (β=-0.02, SE=0.01, p=0.006), and sleep apnea (β=-0.01, SE=0.01, p=0.018). Our results suggest that APOE-ϵ4 is associated with decreased problems in snoring and sleep apnea, in non-demented older adults.

[Familial clustering of symptoms typical for OSAS]

The aim of the study was to compare the incidence of obstructive sleep apnoea syndrome (OSAS) symptoms in relatives of subjects with OSAS and in relatives without OSAS but with clinical symptoms of this disease. The study group consisted of 186 relatives of patients with OSAS and 117 relatives of patients with symptoms of OSAS in whom the disease was not confirmed by polysomnography. They were all mailed a questionnaire with questions concerning anthropometric data, the presence of symptoms typical for OSAS and the presence of concomitant diseases. Analysis of the obtained data revealed an increased frequency of snoring, sleep apnea and nycturia in the relatives of patients with OSAS when compared to relatives of patients without OSAS, but the difference was not statistically significant. The incidence of daytime OSAS symptoms was significantly higher in the group of relatives of patients with OSAS. No differences in the incidence of arterial hypertension, ischaemic heart disease and diabetes mellitus were found.

Influence of HLA antigens and OSAS in childhood: a preliminary report

Several studies have emphasized the role of familial factors and familial aggregation in increasing susceptibility to obstructive sleep apnea syndrome (OSAS); the aim of the present study was to investigate the possible influence of human leukocyte antigen (HLA) in the development of sleep disordered breathing and OSAS of children. Between January 2000 and January 2003, all the 370 children [193 males; median age: 5.2 years (range: 1-12 years)] with sleep disordered breathing referred to our Center were screened by a 41-item multiple-choice questionnaire. All habitual snores children underwent a polisomnographic evaluation, and those with an apnea/hypopnea index >3 were diagnosed as having OSAS. All children with OSAS or primary snoring were HLA typed for class I and II. According to nocturnal polygraphic monitoring study, 41 patients were diagnosed as having OSAS and 32 as primary snoring. Patients in the two diagnostic groups were homogeneous for demographic and clinical characteristics. HLA-B65 was found to be significantly more expressed in children with sleep disordered breathing as compared with controls (10.5% versus 3.61; Pypc < 0.04) while no difference was found for the other tested antigens. A logistic regression analysis found cough (P < 0.02) and persistent wheeze (P < 0.008) the sole risk factors for OSAS development. Our preliminary data suggest that HLA does not play a key role in the pathogenesis of OSAS, however more studies are needed to clarify this issue.

Genetic Influences in Self-Reported Symptoms of Obstructive Sleep Apnoea and Restless Legs: A Twin Study

Sleep disorders, such as obstructive sleep apnoea (OSA) and restless legs syndrome (RLS), are very common. The relative importance of genetic and nongenetic (environmental) influences on the symptomatology of these conditions has not been well studied. This study uses the twin design to examine this by evaluating OSA and RLS symptoms in monozygotic (MZ) and dizygotic (DZ) twins. Six thousand six hundred unselected female twin pairs, identified from a national volunteer twin register, were asked to complete a medical questionnaire. This questionnaire included questions on OSA and RLS symptoms, as well as questions on subject demographics, past medical history, smoking history and menopausal status. Responses were obtained from 4503 individuals (68% response rate). A total of 1937 twin pairs were evaluable: 933 MZ pairs (mean [range] age 51 [20-76] years) and 1004 DZ pairs (age 51 [20-80] years). Concordance rates were higher for MZ than DZ twins for OSA and RLS symptoms. Multifactorial liability threshold modeling suggests that additive genetic effects combined with unique environmental factors provide the best model for OSA and RLS symptoms. Heritability was estimated to be 52% (95% confidence interval 36% to 68%) for disruptive snoring, 48% (37% to 58%) for daytime sleepiness, 54% (44% to 63%) for restless legs, and 60% (51% to 69%) for legs jerking. These estimates dropped only slightly after adjustment for potential confounding influences on the symptoms of snoring and daytime sleepiness. These results suggest a substantial genetic contribution to the symptomatology of OSA and RLS. More research is needed to identify the genes responsible, and may ultimately lead to new therapies.

The familial aggregation of pediatric obstructive sleep apnea syndrome

OBJECTIVE

To determine the role of genetic mechanisms in the development of pediatric obstructive sleep apnea syndrome (OSAS).

DESIGN

Genetic-epidemiologic survey of families of index children with laboratory-confirmed OSAS.

SETTING

Tertiary care academic medical center.

PARTICIPANTS

Six-hundred nap polysomnograms performed in our institution's pediatric sleep laboratory over a 6-year period (1994-2000) were reviewed, and the 497 children who tested positive for OSAS were selected. A caretaker of 200 of these index patients was contacted, and 115 were enrolled in the study.

INTERVENTION AND MAIN OUTCOME MEASURE

Questionnaire-type telephone interviews were conducted with the current caretakers of the index patients to assess the distribution of sleep-disordered breathing in the first-degree relatives.

RESULTS

Data were collected for 445 first-degree relatives (256 adults and 189 children) of the 115 index patients. Habitual snoring was found in 194 (43.6%) of the family members, while symptoms highly suggestive of OSAS (nighttime "gasping for air" or "cessation of breathing") were found in 91(20.4%). Sixty-eight (26.6%) of the adult first-degree relatives and 23 (12.2%) of the pediatric first-degree relatives had symptoms highly suggestive of OSAS. Of the 115 index children, 50 (43.5%) had at least 1 relative with symptoms highly suggestive of OSAS; 6 (1.3%) of the first-degree relatives had sleep study results positive for OSAS, 4 (0.9%) were using nasal continuous positive airway pressure, and 21 (4.7%) had prior surgery for the treatment of OSAS.

CONCLUSION

Considering the established prevalence of OSAS in the general population (2%-4%), the results of this study support a familial basis for this disorder.

Genetic factors in self-reported snoring and excessive daytime sleepiness: a twin study

Subjects in this study included 1,560 intact male-male twin pairs (818 monozygotic [MZ], 742 dizygotic [DZ]) of mean age (+/- SD) 74.2 +/- 2.8 yr. The Epworth Sleepiness Scale (ESS) was used to assess daytime sleepiness and standardized questionnaires assessed snoring. Multivariate genetic model fitting was used to estimate the contribution of genetic and nongenetic (environmental) influences to the variation and covariation of obesity with snoring and daytime sleepiness. In this sample, 26% were habitual snorers, 18% reported excessive daytime sleepiness (ESS > or = 11), and 29% were obese (body mass index [BMI] > or = 28). By using structural equation modeling, we estimated that genetic factors accounted for 64% of the variance in obesity, 40% of the variance in daytime sleepiness, and 23% of the variability in self-reports of snoring. We found a significant genetic correlation between obesity and snoring and between obesity and excessive daytime sleepiness (EDS), although for the most part the genetic variance in snoring and sleepiness was nonoverlapping with the genetic variance for obesity. We conclude from these data that self-reported symptoms of snoring and daytime sleepiness in older men have a genetic basis that is largely independent of genes associated with obesity.

Normative data on snoring: a comparison between younger and older adults

Snoring is a common sleep-related behaviour. Increased body mass index (BMI), cranio-facial anatomical features, and older age have been linked to the occurrence of snoring. While mostly middle-aged populations have been studied for the occurrence of snoring and sleep-related breathing abnormality, this study was designed to assess the subjective report of snoring and the objective measurement of snoring at the two extremes of human age. The study design called for measurement of snoring in two age groups (college students; n=155 and older subjects; mean age 64.1 yrs n=134) with a mean age difference of 45 yrs. Snoring was assessed with a validated recording device. A validated questionnaire was used to subjectively assess snoring and obtain relevant sleep-related information. Students and older subjects differed in the self-report of snoring. While 83% of students reported "never" or "rarely" snoring only 35% of older subjects fell into these categories. Measurement of snoring during sleep revealed that students spent more time during sleep with continuous snoring than older subjects. In older subjects, a reduction in continuous snoring was accompanied by an increase in apnoeic snoring. Subjective snoring frequency correlated with continuous snoring in students only. A positive family history of snoring increased the odds ratio for self-reported snoring but not for recorded snoring. It has been shown that snoring frequency can vary depending on age and that the congruency between perceived snoring frequency and recorded snoring is influenced by the age of an individual.

Snoring, family history, and genetic markers in men. The Copenhagen Male Study

BACKGROUND

No studies have attempted to examine the genetic influence on the habit of snoring. The aim of the present study was to examine whether an association existed between self-reported snoring and family history of snoring and a number of genetic markers.

MATERIAL AND METHODS

The data were derived from a primarily cardiovascular disease cohort study of 3,387 men aged 54 to 74 years. A number of sleep-related questions were included. Some 3,308 men had given valid questionnaire information on snoring and whether they had their own bedroom due to snoring and were regarded eligible for the present study. Men who reported that they snored often or always were considered habitual snorers, and those who reported that they seldom or never snored were considered nonsnorers. We considered habitual snorers who reported that they had their own bedroom due to snoring to be a group with a presumably more severe form of snoring. Information about other health and lifestyle parameters was obtained from a comprehensive questionnaire. Four major blood groups were determined: ABO, Rhesus, MNS, and Lewis, together with complement C3. A saliva sample was taken for determination of ABH secretor status.

RESULTS

There was a strong relationship between habitual snoring and family history of snoring among grandparents, parents, siblings, and children. Odds ratios were from 2.4 to 4.2, and all associations were significant (p < 0.05). In multivariable analysis, the factor which most strongly separated habitual snorers from nonsnorers, was self-reported habitual snoring among family members. Looking at habitual snorers only, the factors most strongly separating those with their own bedroom due to snoring from those without, were the Lewis blood group phenotype, Le(a+b-) (29.6 vs 18.8%; p < 0.001; age, 63.4 vs 62.1 years; p < 0.01), and selfreported family history of habitual snoring (35.2 vs 29.0%; p < 0.05).

CONCLUSION

There was an overall strong association between habitual snoring and family history of snoring. Among habitual snorers, two genetic markers and age, were the only factors that separated men who had their own bedroom due to snoring from others. The results of this study indicate that snoring, to some extent, is hereditary.

Assessment of the role of inheritance in sleep apnea syndrome

Several reports have suggested a genetic importance in the pathogenesis of the sleep apnea syndrome (SAS). In this study, all adult (> 16 yr of age) offspring of 45 randomly selected parents with previously diagnosed SAS were asked to undergo a whole-night polysomnographic study. One hundred and five of 120 candidates participated in the study (66M:39F), with a high rate of compliance. Forty-seven percent of the offspring (36 males and 13 females; mean age, 32 yr) were found to have SAS. These results appear considerably higher (p < 0.001) than the common estimation of the prevalence of SAS in the population (4%). Another 21.9% of the offspring were "simple snorers" (17 males and 6 females; mean age, = 26 yr). Thirty-one percent were unaffected (13 males, 20 females; mean age, 29 yr). Only 16% of males over 35 yr of age were unaffected. In the single family studied in which both parents were affected, all three of their children (sons) had SAS: two grandsons older than 16 yr were simple snorers. Considering the well-established prevalence of SAS in the general population (1 to 4%), these results may suggest that SAS is an inherited syndrome.

Is the sleep apnoea/hypopnoea syndrome inherited?

BACKGROUND--The aetiology of the sleep apnoea/hypopnoea syndrome (SAHS) is unclear in many patients. Snoring, a prerequisite for SAHS, runs in families. A study was carried out to determine whether there is an increased frequency of irregular breathing during sleep in relatives of patients with SAHS. METHODS--A prospective study was performed of first degree relatives of 20 consecutive non-obese (BMI < 30 kg/m2) patients with SAHS. Questionnaires on SAHS symptoms were sent to all first order relatives and those living within 150 miles of Edinburgh were invited for overnight monitoring of their breathing, sleep, and oxygenation patterns in the sleep laboratory. RESULTS--Ten of the 40 relatives had more than 15 apnoeas + hypopnoeas/hour of sleep, and eight had more than five 4% desaturations/hour. These frequencies of irregular breathing and desaturation are significantly higher than in the British population. Cephalometric studies showed no skeletal abnormality but an increased uvular width was found in the affected relatives. CONCLUSIONS--There is an increased frequency of abnormal breathing during sleep in relatives of non-obese patients with SAHS.