Scientists have identified the cause of a chronic cold hand condition that is causing suffering to hundreds of millions of people worldwide.
The first study of its kind found that people diagnosed with Raynaud’s syndrome have mutations in two genes – one linked to stress and the other to embryonic development.
Researchers say the discovery could open up new therapeutic options that more specifically target the underlying genetic cause of the disease.
Dr. Emma Blamont, UK research lead in scleroderma and Raynaud’s disease, said: “For the millions of people living with the disease, simple everyday tasks can be challenging, so research like this advances our understanding of Raynaud’s and the role it plays in “Genetics can play a role in its development and is of crucial importance.”
Raynaud’s disease, which affects an estimated two to five percent of people, causes small spasms in the blood vessels that cut off the blood supply to the fingers and toes.
It is the body’s response to cold temperatures in which smaller arteries that supply blood to the skin narrow dramatically, restricting the blood supply to certain areas of the body – most commonly the fingers, but sometimes the toes, ears and the tip of the nose.
Raynaud’s disease, which affects an estimated two to five percent of people, causes small spasms in the blood vessels that cut off the blood supply to the fingers and toes
Those affected often feel numbness in these areas as blood circulation is restricted and the skin turns white.
While health experts have identified risk factors and lifestyle or medical problems associated with the syndrome, no known genetic cause has been discovered.
In a paper published in the journal Nature Communications, researchers in the United Kingdom and Germany conducted the largest genetic study of the condition.
They used electronic medical records from the UK Biobank, a database containing genetic and health information from 439,294 people.
The team identified 5,147 people diagnosed with Raynaud’s and discovered a variation in two genes that predisposed people to the syndrome.
One variant was the alpha-2A adrenergic receptor for adrenaline, or ADRA2A. This is a stress receptor that causes small blood vessels to contract.
Maik Pietzner, lead co-author and professor of health data modeling at Queen Mary University of London, said: “This makes sense when it is cold or dangerous, because the body needs to supply blood to the inside of the body.”
“In Raynaud’s patients, this receptor seemed to be particularly active, which could explain the vascular spasms, especially in combination with the second gene we found.”
The second variant was IRX1, a type of protein that has been shown to be involved in early embryonic development and cell differentiation.
Professor Pietzner said: “This gene is the transcription factor IRX1, which may regulate the ability of blood vessels to dilate.”
“When its production is increased, it may activate genes that prevent narrowed vessels from relaxing as they normally do.
“Together with the overactive adrenaline receptor, this can then result in the vessels not supplying sufficient blood over a prolonged period of time, resulting in the white fingers and toes observed.”
The researchers were able to reproduce some of their findings using data from people of British Bangladeshi and Pakistani origin.
The team also found that people with a genetic predisposition to low blood sugar levels are at increased risk of the syndrome, suggesting that people should avoid prolonged periods of low blood sugar levels.
The researchers’ findings help to understand for the first time why the small vessels in patients react so strongly even without external stimuli such as exposure to cold.
There are two main types of Raynaud’s: primary and secondary.
When Raynaud’s symptoms first appear, the fingers turn white because blood circulation is restricted. When the tissue loses oxygen, the fingers turn bluish. As blood flow returns, the fingers become red and may experience tingling, swelling, and/or painful throbbing
While health experts have identified risk factors and lifestyle or medical problems associated with the syndrome, no known genetic cause has been discovered
The primary condition is the most common and is not due to any illness a person may have. It can be so mild that the person may not need treatment. It can also disappear on its own.
Secondary Raynaud’s syndrome develops due to another health condition. It occurs less frequently than the primary disease, but is often more serious.
Health experts have identified possible lifestyle and medical causes of the disease, which may include smoking, certain medications, connective tissue disorders, artery disease and carpal tunnel syndrome.
They identified risk factors including age, gender, climate and family history. Raynaud’s syndrome affects women more often than men and most commonly occurs between the ages of 15 and 30. If parents, siblings or children have the syndrome, the risk of primary Raynaud’s syndrome appears to increase.
When Raynaud’s symptoms first appear, the fingers turn white because blood circulation is restricted. When the tissue loses oxygen, the fingers turn bluish. As blood flow returns, the fingers become red and may experience tingling, swelling, and/or painful throbbing.
There is no cure or current treatment for the syndrome. The goal is to relieve symptoms by reducing their frequency and severity.
Dr. Blamont added: “The next step is to confirm these important results in more diverse populations and to validate the results through functional studies.” If successful, these results could help us develop further new therapeutic options for Raynaud’s, leading to better, would lead to more targeted and gentle treatments.”
The study also “systematically highlighted opportunities for drug reuse, such as the use of the antidepressant mirtazapine in people with Raynaud’s.”
Claudia Langenberg, lead co-author and professor at the Berlin Institute of Health, added: “Of course we hope that our results will ultimately point to new treatment options.”
“Approved drugs that more or less specifically inhibit the function of ADRA2A, such as the antidepressant mirtazapine, already exist, and our results suggest that these may represent alternative treatment options for patients suffering from Raynaud’s symptoms.”