Should Family Members Get Tested for Heritable PAH?

If you have been diagnosed with idiopathic or heritable pulmonary arterial hypertension (PAH), it is natural to worry about the risk to your children or siblings. The short answer is that genetic evaluation should start with you, the diagnosed patient. Relatives are generally only offered targeted genetic testing if a clear, disease-causing genetic mutation is first identified in you ^[1].

Because PAH can be linked to several different genes, testing your family members without first knowing exactly which genetic mutation to look for is like searching for a needle in a haystack. Only after a specific mutation is identified in you can your relatives be accurately tested for that exact same mutation ^[1][2].

Step 1: Testing the Diagnosed Patient First

Current medical guidelines recommend that anyone diagnosed with idiopathic or heritable PAH be offered genetic counseling and testing ^[1][3]. A modern genetic test will look for a panel of genes that have definitive, proven links to PAH. As evidence evolves, gene panels change, but currently, experts recognize about 12 definitive PAH genes ^[4].

The most important genes typically included are:

• BMPR2: The most frequent genetic cause of PAH. Depending on the study cohort, it is found in roughly 55% of families with a history of the disease and about 10% of cases that appear to be isolated ^[5].
• SOX17 and TBX4: These are also definitively linked to PAH. They are especially important to test for because they are often associated with pediatric (childhood-onset) PAH, or PAH that occurs alongside congenital heart disease or certain skeletal and lung issues ^[4][5][6].

Step 2: Testing Family Members (Cascade Screening)

If your genetic test reveals a pathogenic or likely pathogenic variant (a known disease-causing mutation), your first-degree relatives (children, siblings, and parents) can then be offered predictive genetic testing, a process known as cascade screening ^[1][2].

For most of these genes, the inheritance pattern is autosomal dominant. This means that if you have the mutation, each of your children has a 50% chance of inheriting it. However, it is crucial to understand the concept of incomplete penetrance: inheriting the mutation does not guarantee a person will actually develop PAH ^[7]. For example, studies suggest only about 20% to 30% of people who carry a BMPR2 mutation will ever develop PAH, though this varies by sex and the specific mutation ^[7][8]. A positive test simply means a person has a higher susceptibility and requires monitoring ^[1].

It is highly recommended to work with a genetic counselor ^[9]. They can help you understand these percentages, discuss family planning (including preconception options), and navigate the ethical and emotional aspects of testing ^[9][10]. For example, the decision of when to test minors can be complex; families must weigh the benefits of early screening (especially if the mutation is linked to childhood-onset PAH like SOX17 or TBX4) against the psychological impact on a child who may not develop the disease until adulthood ^[10][1].

Step 3: Screening Asymptomatic Family Members

If a healthy family member tests positive for the family’s PAH mutation, they will need regular medical surveillance coordinated by a specialized pulmonary hypertension center ^[11][1]. There is no single universal protocol, as screening is tailored to the specific gene, the person’s age, and family history.

• Regular Echocardiograms: For asymptomatic individuals with a BMPR2 mutation, guidelines frequently recommend an annual screening echocardiogram (an ultrasound of the heart) ^[11][1].
• Multimodal Screening: Because an echocardiogram and standard blood tests like NT-proBNP (a marker of heart strain) can sometimes appear normal in the very early stages of PAH, specialized centers often use a broader approach ^[11][12]. This might include electrocardiograms (ECGs), pulmonary function tests, and exercise testing ^[11].
• Right Heart Catheterization: If screening tests or symptoms raise genuine suspicion, specialists may recommend a right-heart catheterization (an invasive procedure that directly measures pressures in the heart and lungs). This is the gold-standard test required to confirm a PAH diagnosis ^[11].

When to Seek Immediate Care: Do not wait for an annual screening if symptoms develop. Family members should promptly contact their clinical team if they experience new or worsening breathlessness, fainting or near-fainting, chest pain, new leg swelling, or a sudden drop in their ability to exercise.

What If Your Genetic Test is Negative or Uncertain?

• Negative Result: If your comprehensive panel finds no mutations, it means no known genetic cause was detected. However, because science has not yet discovered every PAH gene, this does not entirely eliminate the possibility of an inherited risk. Predictive genetic testing cannot be offered to your relatives, but your doctor may still recommend they undergo clinical monitoring based purely on your family’s medical history ^[5][1].
• Variant of Uncertain Significance (VUS): Sometimes a test finds a genetic change, but there isn’t enough medical evidence to know if it causes PAH or is just a harmless variation. A VUS should not be used to test relatives or change medical care ^[4].