top of page

Overview 

Activated PI3K Delta Syndrome (APDS) is a rare primary immunodeficiency that affects immune function. People with APDS may have lower levels of important immune cells, making it harder for the body to fight infections caused by viruses and bacteria.
 

APDS can affect each person differently. Some individuals experience frequent or severe infections and inflammation, while others may have milder symptoms or remain undiagnosed for years.

Causes

APDS is caused by changes (variants or mutations) in the PIK3CD or PIK3R1 genes. These genes help control an enzyme called PI3K delta, which plays an important role in how immune cells grow, communicate, and fight infections.
 

There are two types of APDS:

  • APDS Type 1 is caused by variants in the PIK3CD gene.

  • APDS Type 2 is caused by variants in the PIK3R1 gene.
     

In people with APDS, these genetic changes cause the PI3K delta pathway to become overactive. This can affect how B cells and T cells develop and function, making it harder for the immune system to respond properly to infections.
 

As a result, individuals with APDS may experience frequent infections, inflammation, swollen lymph nodes, and other immune-related complications. In some cases, APDS may also increase the risk of lymphoma, a cancer that affects the lymphatic system.

Group Hug Outdoors

Inheritance

APDS is an autosomal dominant condition, which means a person only needs one altered copy of the gene to have the disorder. Everyone inherits two copies of each gene—one from each parent.
 

If a parent has APDS, each child has:

  • a 50% chance of inheriting the altered gene and developing the condition

  • a 50% chance of inheriting the unaffected gene
     

Approximately 80% of people diagnosed with APDS inherit it from an affected parent, while about 20% develop APDS from a spontaneous (de novo) genetic change.

Diagnosis & Management

Diagnosing APDS can be challenging because symptoms can vary widely from person to person. APDS is sometimes misdiagnosed as other primary immunodeficiencies, including Common Variable Immunodeficiency (CVID) or Hyper IgM Syndrome.
 

Genetic testing that looks for changes in the PIK3CD or PIK3R1 genes can help provide a clear and accurate diagnosis.
 

Management of APDS is individualized and may include immunoglobulin therapy, targeted treatments, infection prevention, and ongoing medical care based on each person’s symptoms and needs.

Father Daughter Embrace

Recently Diagnosed?

Receiving a new APDS diagnosis can feel overwhelming, but you don’t have to navigate it alone. We’re here to provide support, resources, and the opportunity to connect through a personal 1:1 meeting.

bottom of page