Immune thrombocytopenia (ITP) isn’t usually considered a genetic condition, but some people are more predisposed to it than others. A combination of genetics and environment influences your risk of developing ITP.

This article will explain the role of genetics in ITP, whether this condition is inherited, and what family history means for your risk. We’ll also cover other inherited thrombocytopenias and how doctors distinguish them from ITP.

Is ITP an Inherited Condition?

ITP is not usually passed down from parents to children in a clear inheritance pattern. Autoimmune disorders like ITP tend to run in families, so there may be some genetic predisposition to them. Some inherited genetic differences may make a person more likely to develop ITP when combined with other factors.

ITP is an autoimmune disease in which the immune system mistakenly targets platelets, the cells that flow in the blood. Antibodies and immune cells may destroy platelets, and the immune response may also reduce the body’s ability to make new platelets.

Having a First-Degree Relative With ITP Affects Your Risk

ITP has been reported in more than one person in the same family. However, familial ITP is rare, and researchers do not know how much having an affected parent or sibling affects a person’s risk.

You share half your DNA with first-degree relatives. You get 50 percent of your genes from your mother and 50 percent from your father. Even though ITP usually isn’t caused by any one specific gene change, you may have a genetic predisposition with many small changes instead.

Certain Gene Variants Affect Immune System Function

Some evidence suggests that many gene changes (genetic variants) make you more susceptible to developing ITP. It likely takes a combination of several gene variants and your environment to affect your immune system and cause ITP.

In ITP, your immune system is dysregulated and overactive. Variants or changes in some immune cell genes may be to blame:

• CTLA4 gene — Some studies have linked certain variants in this immune-system gene to a greater chance of developing ITP. These findings show a possible association, but they do not prove that a CTLA4 variant directly causes ITP.
• INFG gene — Some studies have linked variants in this immune-system gene to ITP. However, more research is needed to understand whether these variants may also influence ITP development.

Familial ITP Is Very Rare

In rare cases, ITP seems to be passed down through family members. One report of nearly 1,800 children with ITP found that around 2 percent had a family history of the condition.

Genetic studies have found a few potential gene changes involved in familial ITP. These are called germline variants. A germline variant is usually present from birth in many or all of a person’s cells and may be passed from a parent to a child.

Talk To Your Relatives About Autoimmune Diseases in Your Family

ITP is divided into two types — primary and secondary. Secondary ITP is linked to another condition or trigger. Possible causes include autoimmune diseases, infections, immune deficiencies, certain blood cancers, and some medications.

Autoimmune diseases linked to secondary ITP include:

• Antiphospholipid syndrome (APS)
• Autoimmune thyroid disease, like Hashimoto’s disease
• Sjögren’s disease
• Systemic lupus erythematosus (SLE), or lupus

Autoimmune diseases themselves usually aren’t inherited. Instead, a combination of your genetics and environmental factors influences their development.

Having a family history of autoimmune diseases contributes to your risk of ITP. Be sure to ask your relatives about any diseases related to ITP. There’s a chance you may have an underlying autoimmune condition causing your symptoms.

What Inherited Conditions Cause Low Platelet Counts?

Low platelet counts are caused by more than ITP. Inherited thrombocytopenias develop from specific gene mutations. We know their inheritance patterns and diagnose them with genetic testing and other blood tests.

Remember that ITP is caused by autoantibodies attacking and destroying platelets. On the other hand, inherited thrombocytopenias are caused by genetic variants that can affect how platelets are made, released, sized, used, or kept alive.

Many inherited thrombocytopenias have other symptoms outside of easy bruising and bleeding. Be sure to share any new symptoms with your doctor so they can order tests to make the correct diagnosis.

Wiskott-Aldrich Syndrome

Wiskott-Aldrich syndrome (WAS) is an X-linked genetic disorder affecting platelets. According to MedlinePlus, WAS primarily affects males, since they only have one X chromosome.

WAS develops from changes in the WAS gene — which makes a protein found in blood cells. Abnormal WAS proteins affect platelet size and levels. People with this syndrome have fewer and smaller platelets, raising the risk of bruising and bleeding.

In addition to platelet issues, WAS also leads to eczema. This is an inflammatory skin condition that causes itchy, discolored patches on the skin, which may look brown, purple, gray, red, or ashen depending on your skin tone.

Common Variable Immune Deficiency

Common variable immune deficiency (CVID) is a disorder that weakens your immune system. Some people with CVID have other autoimmune problems — most commonly ITP.

Many different gene variants can cause CVID or a condition that looks like CVID. Genetic testing is finding causes in a growing number of people, especially those who develop symptoms early or have several affected family members.

Many people with CVID do not have a known single-gene cause. When a genetic cause is found, the inheritance pattern depends on the gene involved. A genetic counselor can explain what the results may mean for family members.

Myosin Heavy Chain 9-Related Diseases

Changes in the myosin heavy chain 9 (MYH9) gene can lead to other disorders affecting your blood, kidneys, and eyes.

People with MYH9-related disease are born with fewer platelets than usual, and many of their platelets are unusually large. Changes in the MYH9 gene interfere with normal platelet formation.

Other health conditions seen in people with MYH9-related disorders include:

• Cataracts — Clouding in the lens covering your eye, affecting your vision
• Hearing loss — Caused by changes in the inner ear that affect hearing
• Kidney disease — Affects the ability to filter toxins and fluid from blood

When Is Genetic Testing Needed for ITP?

Genetic testing may be recommended to rule out ITP and diagnose an inherited thrombocytopenia instead.

Why Do Doctors Order Genetic Testing?

Primary ITP refers to ITP when doctors can’t find an underlying cause. Some people are mistakenly diagnosed with primary ITP when they have an inherited condition instead. Genetic testing helps rule out other causes and make a final diagnosis.

Since it’s very rare for ITP to run in families, having a family history of thrombocytopenia actually points to a genetic disorder instead of primary ITP. Be sure to let your doctor know if any parents or siblings also have low platelet levels.

Your doctor may also suggest additional testing if your ITP treatment plan isn’t working. This is a sign that some other problem is causing your low platelet levels.

How Does Genetic Testing Work?

Next generation sequencing (NGS) finds rare genetic variants responsible for causing inherited thrombocytopenias. Many genetic tests need a small blood or saliva sample to complete.

Specialists like genetic counselors can walk you through genetic testing and what the results mean. They can order additional testing and help you navigate a new diagnosis. If you have a hereditary bleeding disorder, a genetic counselor will explain the risks to your family members — including children.

Talk To Your Doctor About ITP

ITP generally isn’t considered a genetic condition. Researchers still don’t know exactly how genetics plays a role in ITP, but more research is being done. Gene variants and family history can play a role, but they don’t guarantee you’ll develop ITP.

Familial ITP is very rare, and another bleeding condition is likely behind your symptoms. Be sure to tell your doctor about your personal and family history of bleeding, bruising, and other ITP symptoms. They’ll run tests to rule out other potential causes and get to the correct diagnosis.