Find out about Activated P13K Delta Syndrome
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About APDS

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APDS, or Activated PI3K Delta syndrome, is a rare primary immunodeficiency that affects 1 to 2 people per million. It occurs when there are abnormal changes to the genes PIK3CD or PIK3R1.

While APDS patients may suffer from a wide variety of symptoms, respiratory symptoms and infections of the ears, sinuses, and upper and lower respiratory tracts are the most common symptoms of APDS usually beginning in early childhood.

Due to the nature of the disease, APDS patients are vulnerable to repeat infections and autoimmune,
neurological, and inflammatory symptoms such as lymphoproliferation, splenomegaly, and even lymphoma.

See the below diagram for more information about some typical APDS symptoms.

Typical APDS Patient Symptoms

Most Common APDS Symptoms

APDS Patients usually suffer from at least two of the below symptoms.

Respiratory Tract Infections and Pneumonia

Chronic Cough
Enlarged Lymph Nodes
Enlarged Spleen

Herpes Infections


Inflamation of the Intestine
Developmental Delay

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Frequently Asked Questions about APDS

What is Activated P13K delta syndrome (APDS)?

APDS is a Primary Immunodeficiency (PID) where white blood cells in the immune system don’t work correctly, particularly ones that are called B cells and T cells. Normally, these cells recognise and attack viruses and bacteria to prevent infection. In patients with APDS, the white blood cells are abnormal so patients suffer from frequent infections in the lungs, nose (sinuses) and ears, and can be at greater risk of developing conditions linked with the overproduction of white blood cells (such as swollen lymph nodes and lymphoma).

How many people around the world suffer from APDS?

APDS affects approximately 1 – 2 people per million and is considered a rare disease.

How do you get APDS?

APDS is a genetic condition and it occurs when there is an abnormal change in either one of two specific genes, the PIK3CD gene or the PIK3R1 gene. The genes are inherited, which means that other family members may also have the same genetic condition. Symptoms of APDS can vary, even within families carrying the same condition.

When do people start to suffer from the symptoms of APDS? NOTE:

APDS symptoms usually begin in early childhood as frequent infections, particularly of the lungs, sinuses, and ears.

Over time, repeated lung infections often lead to a condition called bronchiectasis, where the airways become inflamed and scarred, resulting in a build-up of mucus, persistent cough, and breathing problems which make the lungs even more prone to infection. It is understood that B and T-lymphocytes are also produced faster than normal, causing them to clump together in the
lymph nodes and spleen, making them large, and resulting in conditions called lymphadenopathy and splenomegaly.

Clumps in the airways and abdomen lead to nodular lymphoid hyperplasia. APDS also increases the risk of developing a form of blood cancer called B-cell lymphoma. In some instances, patients have experienced neurological dysfunction causing cognitive delay and short syndrome.

Abnormal B- and T-cells can also mistakenly attack normal body cells; this is known as autoimmunity, which may result in conditions such as anemia or low platelet counts where the body cannot form blood clots and can cause severe bleeding. In some cases, patients may appear to develop autoimmune disease of an inflammatory nature.

How do I know if I have APDS?

Patients are often misdiagnosed with other Primary Immunodeficiency diseases such as Common Variable Immunodeficiency (CIVD) and Hyper-IgM before a confirmed APDS diagnosis is made. A suspicion of APDS may be observed by a doctor through laboratory tests and flow cytometry, though a confirmed diagnosis can only be made following a genetic test.

Living with APDS

Lifestyle adjustments may be necessary for many APDS patients and will depend on the severity of symptoms. Reducing exposure to potential community and environmental risks where bacteria and viruses are present is often required. Regular contact with your treating physician is encouraged.

Clinical trials are currently underway for potential treatments that may help to correct the genetic abnormalities that cause APDS.

Just test for APDS

“Typically, a person with APDS will present to a hospital within the first 5 years of life with a predominant and recurring respiratory tract infection. They can also present with swollen lymph nodes. Unfortunately, these general patient symptoms often result in medical professionals pre-diagnosing a range of autoimmune disorders before Primary Immunodeficiency (PI) diagnosis is considered.

Even if a PI Classification is given, a patient can be misdiagnosed with Common Variable Immune Deficiency (CIVID) and Hyper-IgM. This leads to APDS patients being cared for by a variety of physicians, and managed by treatments that don’t address the underlying genetic defect.”

Nicholas Hartog, MD, is a board-certified paediatric and adult allergy and immunology physician.