Canker sores, medically known as recurrent aphthous stomatitis (RAS), are common, recurring small, painful ulcers inside the mouth. They typically have a white or yellow center with a red border and usually heal within 7 to 14 days. Canker sores are not contagious and differ from cold sores, caused by the herpes virus and appearing on the lips. While the exact causes are complex, they involve various interacting factors.
The Role of Heredity
Research indicates a hereditary component influencing the likelihood of developing canker sores. Family studies show a significant association between parental history of canker sores and their children developing the condition. If both parents experience the condition, their child’s risk of sores can be as high as 90%.
Conversely, children with no family history of canker sores have a much lower estimated risk, around 20%. Twin studies further support this genetic link, revealing a higher incidence of canker sores in identical twins compared to fraternal twins. This pattern suggests that inherited factors play a significant role in an individual’s susceptibility to these ulcers.
Identifying Genetic Markers
The biological basis for this hereditary link involves specific genes, particularly those associated with the immune system. Variations in Human Leukocyte Antigens (HLA) types, such as A2, A11, B12, and DR2, have been observed more frequently in individuals prone to canker sores. These HLA genes present antigens to immune cells, influencing how the body recognizes and responds.
Genes responsible for producing interleukins, proteins regulating immune responses, are also implicated. Polymorphisms in genes like IL-1B and IL-6 have been shown to increase the risk for canker sores. These genetic variations can lead to an overactive or dysregulated immune reaction within the mouth’s lining, contributing to the formation of ulcers.
Interaction with Environmental Triggers
While genetics predisposes an individual to canker sores, having certain genetic markers does not guarantee their appearance. Instead, these genetic factors create a heightened susceptibility that, when combined with specific environmental triggers, can lead to an outbreak. This interaction highlights that both inherited traits and external influences are involved in the development of these sores.
Common environmental triggers include minor physical trauma to the mouth, such as accidental biting of the cheek or lip, aggressive toothbrushing, or irritation from dental appliances. Emotional stress and hormonal fluctuations, like those occurring during menstruation, can also act as precipitating factors. Dietary sensitivities may also trigger sores in susceptible individuals, including:
- Chocolate
- Coffee
- Strawberries
- Nuts
- Cheese
- Acidic items
- Ingredients like sodium lauryl sulfate in some toothpastes