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Understanding 
primary HLH

Finding out that you or your loved one have primary HLH can be overwhelming. The following information is for you and your family to learn about primary HLH, its symptoms, and what you might expect after diagnosis.

What is primary HLH?

Primary HLH is a rare genetic condition, which means it can be passed down in families. It usually affects babies and young children, but it can affect older children and adults as well.

Primary HLH is caused by a genetic mutation that keeps the immune system from working properly.

  • When the immune system is working properly, it finds and attacks foreign invaders like viruses and bacteria to protect the body
  • In people with primary HLH, the immune system doesn’t work right. It attacks a person’s own cells and organs instead 
What does pHLH stand for?

primary hemo phagocytic lympho histiocytosis

genetic/​​inherited(also called familial)

blood

cells that eat

relating to the lymphatic system

an excess of macrophages (a type of white blood cell)

Here's how to pronounce primary HLH

What is the difference between primary and secondary HLH?

While researchers are still working to fully understand HLH, so far it is known to exist in 2 main types: primary and secondary.

Primary HLH could be inherited, which means it is passed down from a parent to a child.
Secondary HLH could be triggered by other medical problems, such as an infection or a disease like cancer.

Although the symptoms for both may be similar, it is thought that each has a different cause and may require different approaches to treatment.

Care Tip
To understand more about your or your loved one’s condition, it’s important to know what happens in the body of someone with primary HLH and what some of the symptoms of primary HLH can be.
Please be sure to speak with your doctor about HLH, including any symptoms.
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Take the next step

Watch to understand how primary HLH is identified and treated.

 

See how primary HLH works and what happens inside the body

WHAT HAPPENS INSIDE THE BODY?

See how primary HLH works and what happens inside the body