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New study sheds light on genetic cause

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New research sheds light on a genetic cause of lupus, an autoimmune disease. Mario Tama/Getty Images
  • Lupus is an autoimmune disease that can cause a variety of symptoms that impact people’s health and well-being.
  • The exact causes why a person develops lupus are unknown, but scientists are continuing their research.
  • A recent study found that a variant of the TLR7 gene caused lupus when introduced into mice, indicating that this gene can cause lupus in some people.

Lupus is a disorder in which the body’s immune system attacks healthy tissue. People with lupus can have symptoms ranging from mild to severe. It is not known exactly what causes the condition.

Researchers are still trying to determine the genetic factors that contribute to lupus. A recent study Posted in Nature found that a specific variant of the TLR7 gene caused lupus when introduced into mice. This discovery could lead to new treatment options.

Lupus is an autoimmune disease where the body attacks and damages itself. The most common type of lupus is systemic lupus erythematosus (SLE). People with lupus may experience periods of remission and then periods when their symptoms worsen.

In general, the disease causes inflammation and a wide variety of symptoms, which can affect many organs and body systems. For example, it can affect joints, skin, kidneys and lungs.

Symptoms may include the following:

  • Pain in joints and muscles, with or without swelling
  • Fevers over 100 degrees Fahrenheit
  • Chest pain due to inflammation of the lining of the lungs
  • Skin rashes, one of the common signs of lupus being the “butterfly shaped” rash
  • Sun sensitivity
  • Kidney problems
  • Extreme fatigue or prolonged fatigue
  • Blood clots
  • Anemia
  • forgetfulness or confusion

Lupus has no cure, so treatment focuses on reducing or preventing symptoms and other health problems caused by the disorder. Scientists don’t know what causes lupus, but genetics likely plays a role. Researchers are still working to discover the impact of specific genes on the development of lupus.

Professor of immunology Claudia Mauriof University College London, explained the following to DTM:

“Although we know that genes, as well as environmental factors, must play a role in the development of lupus, to date we do not fully understand which genes are most important. Generally, we think that lupus is caused by the patient having multiple changes in a number of genes that all predispose the patient somewhat to getting the disease.

“However, there is growing evidence that changes in single genes can lead to the very early development of severe disease in childhood,” she added. Professor Mauri was not involved in the new study.

Although more than one genetic factor may contribute to lupus, the researchers in the present study were interested in studying the toll-like receptor-7 (TLR7) gene. In fact, there is growing evidence that TLR7 may play a role in the LED development.

In this study, researchers looked at the genes of a girl with a severe case of lupus. Doctors diagnosed him with the disease when he was 7 years old. They carefully examined his genes and found a distinct mutation in the TLR7 gene.

When they introduced this gene into mice, the rodents developed lupus. They took an in-depth look at the symptoms the mice developed, including the actions of the mice’s B cells, a specific type of white blood cell.

Author of the study, Carola VinuseaProfessor of Immunology at the Australian National University and Director of the Center for Personalized Immunology (CPI), explained: “This is the first time that a TLR7 mutation has caused lupus, providing clear evidence that this disease can occur .”

Professor Mauri was also enthusiastic about the results of the study and explained to DTM:

“This paper shows for the first time that changes in one of the genes researchers thought to be involved in lupus, TLR7, actually led to the development of lupus in a 7-year-old child. This is a very important finding both for confirming the role of this gene in lupus and for understanding more broadly the disease processes that lead to symptoms in patients with lupus.

Although not mentioned by the researchers, the study has some limitations. First, the gene variant was introduced into mice, so researchers should exercise caution when translating the results into humans.

Second, the gene was found primarily in one person, which means further testing should confirm the presence of this genetic mutation in other people with lupus.

When asked to comment on the study, Honorary Consultant Rheumatologist at University College London Hospitals in the UK, Professor Mike Ehrenstein, was optimistic about the study. He was excited about the potential treatments this could lead to.

He said: “This study shows that mutations in TLR7 can cause lupus or at least juvenile lupus. Often children with lupus have more severe disease and the genetic contribution may be greater than in adults.

“The link between TLR7 and lupus dates back over 15 years, and companies have inhibitors in development, so hopefully we’ll hear about their effectiveness soon. Interestingly, hydroxychloroquine, a drug commonly used to treat lupus, can partially work [by] inhibiting TLR7.

Professor Mauri noted that research could focus more on the actions of B cells:

“The researchers elegantly show that the TLR7 mutation in the patient causes hyperactivation of B cells when the same mutation is introduced into an animal model. In fact, in these mice, B cells fire up in parts of the spleen and lymph nodes where they’re not supposed to. Future research will try to understand if this abnormal activation of B lymphocytes is a pathogenic factor present in all types.

Understanding the genetic causes of lupus could also open up new treatment options for people with the disease.