Blau syndrome is a very rare genetic inflammatory condition. Its symptoms can affect various areas of the body, most often the skin, joints, and eyes.
This health condition may occur in fewer than 1 in 1 million children worldwide.
Blau syndrome has several other names, including:
- early onset sarcoidosis
- pediatric granulomatous arthritis
- arthrocutaneouveal granulomatosis
- Blau-type familial granulomatosis
- familial juvenile systemic granulomatosis
In this article, we describe what Blau syndrome is and what causes it. We also explore its symptoms, possible complications, and treatments.
Blau syndrome is an inflammatory disorder that typically targets the skin, joints, and eyes.
Less frequently, the syndrome affects the:
- lymph nodes
- blood vessels
In some people, Blau syndrome causes:
The condition is genetic, and it typically causes symptoms or signs before the age of 4.
The indications of Blau syndrome vary from person to person, and they change as the disease progresses.
The earliest symptom is usually granulomatous dermatitis, a type of skin inflammation that causes a continuous rash. The rash may be scaly or form hard lumps under the skin. It may develop on the arms, legs, and torso.
The appearance and progression of the symptoms vary, but one study found that the rash tends to develop around 1 year of age, joint issues tend to appear by the age of 2, and eye disease by the age of 4.
Conditions that commonly occur with Blau syndrome include:
- inflammation of tendons around the joints
- fluid accumulating around the joints
- inflammation of the eye’s middle layer, the uvea
- conjunctivitis, sometimes called pink eye
- kidney disease
- calcium deposits in the kidneys
- inflammation of the blood vessels
- permanent bending of toes and fingers
Less commonly, Blau syndrome causes inflammation in vital organs and blood vessels, reducing their function and causing serious complications.
According to the Genetic and Rare Diseases Information Center, 80–99% of people with Blau syndrome experience:
- joint pain
- patchy, darkened skin
- corneal inflammation
- decreased joint mobility
Symptoms that 30–79% of people experience include:
- permanent bending of the fingers and toes
- cataracts, or clouding of the eye’s lens
- extreme light sensitivity
Symptoms that 5–29% of people experience include:
- open skin sores
- loss of vision
- altered saliva production or drainage
- swollen lymph nodes
- increased blood pressure
- breathing problems
- reduced or abnormal nerve function
- dry mouth
Blau syndrome is a monogenic disease. This means that it occurs due to a single modification in one gene present in all of the body’s cells.
Blau syndrome seems to result from a single mutation in the NOD2 gene. This gene produces proteins responsible for important immune responses, including inflammation.
Typically, inflammation occurs when immune molecules send white blood cells and signaling molecules to destroy or disable foreign microbes or help with tissue repair.
The mutation associated with Blau syndrome causes NOD2 to produce overactive proteins, resulting in abnormal inflammatory reactions. Researchers are still unsure how overactive NOD2 proteins produce the specific pattern of inflammation that Blau syndrome causes.
Blau syndrome can be inherited, but some people are born with the genetic mutation without having a family history of the issue.
There is no cure for Blau syndrome, but there are ways to manage the symptoms.
According to a 2015 article, high doses of corticosteroids may help reduce inflammation when symptoms flare up. Lower doses can help between flare-ups.
Immunosuppressant medications can also help, alongside steroids.
In addition, medications, such as adalimumab, that counter tumor necrosis factor-alpha seem to help reduce inflammation in combination with corticosteroids, immunosuppressants, or both.
Because of the condition’s rarity and its genetic basis, several specialists may be needed to diagnose Blau syndrome.
The Genetic and Rare Diseases Information Center provide advice on finding a specialist here.
To diagnose the condition, a doctor will first review the personal and family medical histories, assess all symptoms, and perform a physical exam.
They may also order laboratory tests to rule out other conditions and check joint fluid and any skin sores for specific markers of Blau syndrome.
If a doctor suspects that a baby has the condition, and the baby has joint, eye, and skin symptoms, they will give a referral for genetic testing.
Genetic testing checks for irregularities in chromosomes, single genes, or bits of DNA, as well as for the activity level or amount of proteins.
The type and severity of Blau syndrome symptoms vary from person to person. The severity tends to increase over time.
One study that included 31 children and adults receiving treatment for the syndrome found that:
- 41% of participants had normal function
- 31% had mild impairment
- 17% had moderate impairment
- 11% had severe impairment
In the same study, 48% of participants reported that Blau syndrome moderately to severely impacted their well-being, while 26% reported no impact. Also, 43% of participants reported experiencing pain.
Blau syndrome is a genetic condition that causes inflammation throughout the body. Signs are usually present before the age of 4.
While there is no cure for Blau syndrome, various medications can help slow its progression and manage symptoms.
Anyone who suspects that they or their child has Blau syndrome should speak with a doctor, ideally a pediatric genetic specialist, as soon as possible.