Introduction: What is Obstructive Sleep Apnea?

Obstructive Sleep Apnea (OSA) is a common, serious, and potentially life-threatening sleep disorder. It is characterized by frequent episodes of partial or complete upper airway obstruction during sleep.
This results in intermittent hypoxemia (low level of oxygen in the blood) and arousal.
Here, the throat muscles relax at irregular intervals and fail to keep the airway open. This results in inadequate breathing for 10 seconds or longer. Thus, the oxygen levels lower, and carbon dioxide levels build up. The brain interprets this as a need to open the airway and wakes you up in the process. This awakening is usually too brief to be remembered. A very noticeable sign of OSA is snoring.

More than 18 million American adults have been estimated to have sleep apnea.

How Does Genetics Influence the Risk of Obstructive Sleep Apnea?

Genes thought to be associated with the development of Obstructive Sleep apnea are involved in many body processes. They include:
- Communication between nerve cells
- Breathing regulation
- Control of inflammatory responses by the immune system
- Development of tissues in the head and face (craniofacial development)
- The sleep-wake cycle
- Appetite control

African-Americans and Pacific Islanders have more genetic variants associated with sleep apnea than Europeans. Variations in genes such as TNF, CRP, PLEK, PTGER3, LPAR1, HTR2A, and GDNF are associated with the risk of obstructive sleep apnea. Studies suggest that variations in multiple genes, each with a small effect, combine to increase the risk of developing the condition.

TNFA Gene and Obstructive Sleep Apnea

The TNFA gene encodes a proinflammatory cytokine (a molecule released by the T-immune cells) that belongs to the tumor necrosis factor (TNF) superfamily. It regulates various biological processes, including cell proliferation, differentiation, apoptosis, lipid metabolism, and coagulation. Studies have shown that TNF is involved in the regulation of sleep by influencing the adenosine receptor expression.

rs1800629 And Obstructive Sleep Apnea

The rs1800629 is G>A polymorphism located in the TNFA gene associated with increased transcriptional activity and higher TNF levels. This SNP has been studied to contribute to the pathogenesis of sleep disorders. Studies have shown that the rs1800629 - A allele carriers are associated with an increased risk of developing obstructive sleep apnea when compared to G allele carriers.

Non-genetic Influences On OSA Risk

Some non-genetic risk factors for OSA are:
- Narrowed airway
- Smoking
- Hypertension
- Obesity
- Gender
- Menopause
- Diabetes

According to a 2013 study, people with type 2 diabetes have nearly a 50% chance of being diagnosed with OSA. Both of these often coexist because of shared risk factors.

Effects Of OSA on Health

Some effects of OSA that could interfere with everyday functioning include:
- Difficulty in concentrating
- Excessive daytime sleepiness
- Irritability, sexual dysfunction
- Nighttime sweating
- Learning and memory difficulties

Tips for Managing Obstructive Sleep Apnea

1. Having a consistent sleep cycle routine, maintaining a healthy weight, avoiding smoking and alcohol consumption, a comfortable bedroom environment, and exercise during the day are some of the lifestyle changes that can help prevent and also manage obstructive sleep apnea.
2. If following lifestyle changes don’t help you manage your sleep apnea, do consult a doctor. This applies to moderate and severe sleep apnea.
3. The doctor may ask you to use an oral device (mouthpiece) designed to keep your throat open and keep your airway open.
4. Positive airway pressure treatment reduces the respiratory events that occur when you sleep, thereby reducing snoring also.
5. In some cases, surgery is also done to manage obstructive sleep apnea.

Summary

1. Obstructive Sleep Apnea (OSA) is characterized by frequent episodes of partial or complete upper airway obstruction during sleep. Snoring is a notable sign of OSA.
2. Variations in multiple genes, each with a small effect, combine to increase the risk of developing the condition.
3. TNFA gene, which encodes a molecule produced by immune cells, is involved in regulating sleep by influencing the adenosine receptor expression. The A allele of SNP rs1800629 is associated with an increased risk of developing OSA compared to the G allele.
4. OSA can lead to difficulties in concentration, learning, memory, excessive daytime sleepiness, and nighttime sweating.
5. A consistent sleep cycle routine, healthy weight, and reducing alcohol consumption are some lifestyle changes to help manage OSA. An oral device and positive airway pressure treatment are also used in some cases under the guidance of a medical professional.

References

https://pubmed.ncbi.nlm.nih.gov/22043116/
https://pubmed.ncbi.nlm.nih.gov/23155414/
https://pubmed.ncbi.nlm.nih.gov/20538960/

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How Does Genetics Influence The Risk Of Obstructive Sleep Apnea