Skin and blood vessels:

• A purple, net-like rash on the skin
• Fingers or toes that turn cold, pale, or blue in cold weather or stress
• Sores in the mouth

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Brain and nerves:

• Stroke at a young age (before age 10), from a blocked or burst blood vessel in the brain
• Sudden weakness, numbness, or tingling in the arms or legs

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Blood and immune system:

• Low blood cell counts, this can cause tiredness and pallor (low red cells), more infections (low white cells), or easy bruising and bleeding (low platelets)
• Getting sick often, or having low levels of the proteins that fight infection
• A swollen liver or spleen

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Other:

• High blood pressure
• Liver damage or scarring over time
• Stomach and gut inflammation that looks similar to inflammatory bowel disease
• Slower growth or development in children

• Eye problems 
• Kidney disease 
• Blood cancers and lymphoma
• Severe bone marrow failure (when the bone marrow stops making enough blood cells)

DADA2 happens because of a change in a gene that normally tells the body how to make a substance called adenosine deaminase 2 (ADA2). Under normal conditions, ADA2 breaks down a molecule that builds up outside cells, and this keeps the immune system calm and balanced. When the gene is changed, the body does not make enough working ADA2. Without it, that molecule builds up and pushes immune cells into an overactive state. These overactive immune cells attack the walls of blood vessels, which is why swelling and irritation can affect so many organs at once.

DADA2 is passed down in an autosomal recessive pattern. This means a child needs two changed copies of the gene , one from each parent , to have the disease. Parents who carry just one changed copy are usually completely healthy themselves.

If both parents are carriers, for each pregnancy:

• About 1 in 4 children will have DADA2
• About 1 in 2 children will be healthy carriers, like their parents
• About 1 in 4 children will not inherit the gene change at all

DADA2 is thought to affect 1 in 222,000 people, meaning about 35,000 people may have it worldwide, though many are likely undiagnosed. It's more common in families where parents are close blood relatives. It affects men and women equally, and some gene changes are more common in certain groups, such as Georgian-Jewish, Turkish, Finnish, and Dutch populations.

Doctors confirm DADA2 with two main tests: a blood test that measures how well the ADA2 enzyme is working (it will be very low or missing), and a genetic test that checks for changes in both copies of the ADA2 gene. Other tests, like blood counts, infection-fighting protein levels, and brain scans (MRI) , help check how much the disease has affected the body. Finding it early is important to help prevent strokes and other serious problems.

Because DADA2 can affect so many parts of the body, care usually involves a team of different doctors, including:

• Joint and blood vessel inflammation specialist (rheumatologist) 
• Immune system specialist (immunologist) 
• Blood disorder specialist (hematologist) 
• Brain and nerve specialist (neurologist) 
• Stomach and gut specialist (gastroenterologist) 
• Liver specialist (hepatologist) 
• Eye specialist (ophthalmologist) 
• Physical and occupational therapist, to help with recovery and daily activities after a stroke or nerve damage 
• Genetic counselor, to explain inheritance and help with family planning 
• Social worker, to connect families with support services

Regular check-ups every 3–6 months with this care team are important for managing the disease over time. Patients are usually placed on anti-inflammatory treatment and corticosteroids but cure lies in stem cell transplantation.

• The DADA2 Foundation (dada2.org) an international group of experts from 18 countries who created shared care guidelines for DADA2, and a place for patients and families to find support and information. 
• National Organization for Rare Disorders (NORD) general DADA2 overview. 
• Orphanet DADA2 disease summary.