Is Progressive Supranuclear Palsy (PSP) Hereditary?

No, for the vast majority of people, Progressive Supranuclear Palsy (PSP) is not hereditary. Having PSP does not mean your children will definitely inherit the disease. PSP is almost always considered a sporadic disorder ^[1][2], meaning it occurs randomly without a clear family link.

Understanding the MAPT H1 Haplotype

Many families reading about PSP will see mentions of genetics, particularly something called the MAPT H1 haplotype. When navigating these terms, it is important to understand the difference between a “risk factor” and a “direct cause.”

The MAPT gene provides instructions for making tau, a protein that builds up abnormally in the brains of people with PSP ^[3]. (While the tau protein is also involved in Alzheimer’s disease, the way genetic risks affect the cells in PSP is entirely different from Alzheimer’s ^[3]). The H1 haplotype is a specific, normal variation of the MAPT gene.

• It is a risk factor: Research shows that the MAPT H1 haplotype is strongly associated with an increased susceptibility to developing PSP ^[4][5]. In fact, the vast majority of people with PSP have this genetic trait.
• It is NOT a diagnosis: This same genetic variation is incredibly common in the general, healthy population. Millions of people have the MAPT H1 haplotype and will never develop PSP or any other neurological disease. Having this variant might slightly increase the risk, but it is not enough on its own to cause the disease.

Other Genetic Markers

Scientists have identified other minor genetic variations in genes like MOBP and STX6 that might also influence a person’s risk of developing PSP ^[6][7]. Like the MAPT H1 haplotype, these are just pieces of a complex puzzle, likely requiring a combination of genetics, aging, and environmental factors to trigger the disease. Currently, the specific environmental triggers for PSP remain unknown.

When is PSP Hereditary?

True familial (inherited) PSP is extremely rare. When it does run in families, it is usually linked to specific, rare mutations in the MAPT gene ^[8] — which are completely different from the common H1 haplotype risk factor. These rare inherited mutations typically cause a broader range of symptoms, often overlapping with conditions like frontotemporal dementia ^[9].

If you do not have multiple family members who were diagnosed with similar neurological conditions, the likelihood of a hereditary form of PSP is minimal. However, if you do have a strong family history of neurodegenerative disease, you should consult a genetic counselor or a neurogeneticist.

Should my family get genetic testing?

Because PSP is primarily sporadic, routine genetic testing for family members is generally not recommended. Commercial genetic testing for the MAPT H1 haplotype is not useful because finding out you have the variant cannot tell you if you will actually develop the disease. If you are concerned about your specific family history, the best first step is to discuss it with your neurologist to completely rule out the rare familial type.