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Living with Familial thrombocytosis

An inherited condition with a persistently high platelet count that can lead to clotting or bleeding problems.

Understanding Familial thrombocytosis

Familial thrombocytosis is an inherited condition with a lasting high number of platelets in the blood.

It can create a tendency toward blood clots and bleeding but does not cause an overgrowth of bone marrow cells (myeloproliferation). It is listed as starting in childhood.

Signs & symptoms

Symptoms vary from person to person. GARD lists these among the most common:

  • High platelet count (thrombocytosis)
  • Blood clots in arteries or veins
  • Abnormal bleeding
  • Headache
  • Chest pain
  • Mini-stroke (transient ischemic attack)

Not everyone has every symptom. GARD's list comes from the Human Phenotype Ontology.

Diagnosis

  1. Talk with your doctor

    Share the symptoms you've noticed, when they started and your family health history. Notes and photos can help.

  2. See a specialist

    Specialists who may be involved include blood and bone marrow specialists and genetic specialists.

  3. Ask which tests can help

    Your care team will decide which exams and tests can confirm the diagnosis.

Care & treatment

Care team
Blood and bone marrow specialists (hematologists); Genetic specialists (geneticists)
Expert care
Ask about multidisciplinary care centers for rare conditions
Treatment
GARD doesn't list specific treatments for this condition. Your care team will tailor care to your symptoms.
Research
Clinical trials and observational studies may be options. See the research section below.

General information, not medical advice. Your care team makes the decisions.

Everyday life

Living with a rare condition is easier with support.

  • Connect with rare disease patient organizations for support
  • Keep notes on symptoms, changes and questions for appointments
  • Ask about patient registries that help research
  • Look into financial aid and travel resources for care visits
Bring these questions to your next doctor visit
What is my platelet count, and how often should it be checked?
What are my clot and bleeding risks?
Is genetic testing available for my family?

Quick facts

Symptoms usually startChild
InheritanceAutosomal Dominant, X-Linked

Changes in genes cause it. It can be passed down in an autosomal dominant or X-linked way.

GeneticBlood

Also known as: familial thrombocythemia; hereditary thrombocythemia; hereditary thrombocytosis; hereditary thrombocytosis disease; thcyt

Patient organizations

Rare-disease groups that can help

Source: NIH GARD · Familial thrombocytosisGARD ID 16688 · GARD page updated September 2026 · Plain-language summary by Know Rare; editorial review pending. General information, not medical advice.

You are more than your diagnosis

Perspectives from people navigating life with Familial thrombocytosis.

Explore the Familial thrombocytosis blog

Explore research for Familial thrombocytosis

Explore actively recruiting Familial thrombocytosis studies with HealthSpark.

HealthSpark

Find actively recruiting studies for Familial thrombocytosis with HealthSpark. Share your city to explore research near you.

  • Recruiting studies from ClinicalTrials.gov
  • Share your city to look for research near you
  • Eligibility is confirmed by the study team

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Powered by HealthSpark, our AI chat helper · Study information from ClinicalTrials.gov · Eligibility is confirmed by the study team.

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