Quebec Platelet Disorder (Bernard–Soulier Syndrome)
Overview
Quebec platelet disorder (QPD) and Bernard–Soulier syndrome (BSS) are rare inherited bleeding disorders that affect platelet function. Although they share some clinical features, they are caused by mutations in different genes and have distinct laboratory findings.
- QPD – caused by a duplication of the PLAUR (urokinase‑type plasminogen activator receptor) gene on chromosome 12, leading to excess urokinase‑type plasminogen activator (uPA) stored in platelet α‑granules.
- BSS – caused by mutations in the genes that encode the platelet glycoprotein (GP) Ib‑IX‑V complex (GP1BA, GP1BB, or GP9). This complex is essential for platelet adhesion to the sub‑endothelial von Willebrand factor.
Both disorders present with a tendency to bleed because platelets cannot adhere properly to damaged blood vessels or have abnormal fibrinolysis.
Who it affects: The conditions are autosomal‑dominant (QPD) or autosomal‑recessive (BSS). They affect males and females equally and are present from birth.
Prevalence:
- QPD – <≈ 1 in 500,000 people worldwide
- BSS – <≈ 1 in 1,000,000 individuals, though prevalence may be higher in populations with consanguineous marriages.
Because the disorders are rare, case series and registry data from the CDC, Mayo Clinic, and the NIH provide the most reliable epidemiologic estimates.
Symptoms
The clinical picture varies from mild bruising to life‑threatening hemorrhage. Common findings include:
- Easy bruising (ecchymoses) – often seen after minor trauma.
- Epistaxis (nosebleeds) – frequent and sometimes prolonged.
- Oral mucosal bleeding – gums may bleed after tooth brushing or dental work.
- Menorrhagia – heavy menstrual periods in women.
- Prolonged bleeding after surgery, dental extraction, or circumcision.
- Gastrointestinal bleeding – occult blood loss leading to anemia.
- Hematuria – blood in the urine after trauma or infection.
- Post‑traumatic intramuscular hematomas.
- Petechiae – tiny red spots on the skin, especially after vigorous activity.
- Joint or muscle bleeds – rare but reported, especially in severe BSS.
In QPD, a characteristic finding is a **delayed** but often massive bleeding episode after a minor injury because the excess uPA accelerates clot breakdown. In BSS, bleeding tends to start early and be persistent due to defective platelet adhesion.
Causes and Risk Factors
Genetic Basis
- Quebec Platelet Disorder: Duplication of the PLAUR gene → over‑production of uPA stored in platelet α‑granules. The excess uPA is released during platelet activation, leading to hyper‑fibrinolysis.
- Bernard–Soulier Syndrome: Loss‑of‑function mutations in GP1BA, GP1BB, or GP9. The GP Ib‑IX‑V complex cannot bind von Willebrand factor, impairing platelet adhesion.
Inheritance Patterns
- QPD – autosomal‑dominant; a single affected parent can transmit the disorder.
- BSS – autosomal‑recessive; both parents must be carriers. Consanguinity increases risk.
Other Risk Modifiers
- Family history of unexplained bleeding or known diagnosis.
- Ethnic background: Certain founder mutations have been identified in French‑Canadian (QPD) and Mediterranean (BSS) families.
- Medications that impair platelet function (aspirin, NSAIDs, clopidogrel) can worsen bleeding.
- Co‑existing disorders such as liver disease or vitamin K deficiency may compound hemorrhagic risk.
Diagnosis
Clinical Evaluation
Diagnosis begins with a thorough bleeding history (using tools like the ISTH Bleeding Assessment Tool) and a detailed family pedigree.
Laboratory Tests
- Complete Blood Count (CBC) – Usually shows normal or mildly decreased platelet count; in BSS, platelets may be unusually large (macrothrombocytopenia).
- Peripheral Blood Smear – Demonstrates giant platelets in BSS; platelet size is generally normal in QPD.
- Platelet Function Analyzer (PFA‑100/200) – Prolonged closure time with collagen/epinephrine cartridge.
- Light Transmission Aggregometry (LTA)
- QPD – normal aggregation with ADP, collagen, and ristocetin, but reduced clot stability due to hyper‑fibrinolysis.
- BSS – absent or markedly reduced aggregation with ristocetin, normal response to ADP and collagen.
- Platelet Flow Cytometry – Measures surface expression of GP Ib‑IX‑V; markedly decreased in BSS.
- uPA Activity Assay – Elevated plasma and platelet uPA activity is diagnostic for QPD.
- Genetic Testing – Targeted sequencing or panel testing for PLAUR, GP1BA, GP1BB, and GP9. Confirmation of pathogenic variants establishes a definitive diagnosis.
Differential Diagnosis
Other inherited platelet function disorders (e.g., Glanzmann thrombasthenia, MYH9‑related disease) and acquired causes of thrombocytopenia must be excluded.
Treatment Options
General Principles
- Goal: prevent or control bleeding while minimizing exposure to unnecessary transfusions.
- Management is individualized based on severity, type of surgery, and personal bleeding history.
Medications
- Antifibrinolytics – Tranexamic acid (TXA) or ɛ‑aminocaproic acid are first‑line for mucosal bleeding, dental procedures, and minor surgeries. In QPD, TXA helps counteract excess uPA activity.
- Desmopressin (DDAVP) – Effective in some BSS patients for mild bleeding, as it raises plasma von Willebrand factor and factor VIII levels, partially compensating for impaired platelet adhesion.
- Recombinant Factor VIIa (rFVIIa) – Reserved for life‑threatening bleeds when platelet transfusion is not feasible.
- Hormonal therapy – Oral contraceptives or levonorgestrel IUD for menorrhagia.
Blood Products
- Platelet transfusion – The most reliable method to stop severe bleeding in BSS. HLA‑matched or washed platelets reduce allo‑immunization.
- Fresh frozen plasma (FFP) – May be used if coagulopathy co‑exists.
Procedural Interventions
- Tranexamic acid mouthwash (4.8% solution) for oral bleeding.
- Topical hemostatic agents (e.g., fibrin sealants, oxidized cellulose) during surgery.
- Dental prophylaxis with local measures and pre‑procedure TXA.
Lifestyle Modifications
- Avoid NSAIDs, aspirin, and other antiplatelet agents unless prescribed for another condition.
- Use protective gear (helmets, padded gloves) during high‑impact sports.
- Maintain good oral hygiene to reduce gum bleeding.
Living with Quebec Platelet Disorder (Bernard–Soulier Syndrome)
Daily Management Tips
- Bleeding diary – Record any bleeding episode, its trigger, and treatment response.
- Regular laboratory monitoring – CBC and platelet function studies every 1–2 years, or sooner after a major bleed.
- Vaccinations – Stay up to date, especially against hepatitis B and influenza, to minimize infection‑related bleeding complications.
- Dental care – Schedule regular cleanings, inform the dentist of the diagnosis, and use pre‑emptive TXA mouthwash.
- Travel preparedness – Carry a “bleeding disorder kit” containing TXA tablets, a written emergency plan, and a donor card for platelet transfusions.
- Genetic counseling – Recommended for affected individuals planning families, to discuss recurrence risk and prenatal testing options.
Psychosocial Support
Connect with patient organizations such as the Bleeding Disorders Community or the Canadian Hemophilia Society. Peer support reduces anxiety and improves adherence to treatment plans.
Prevention
- Educate caregivers and schools about the disorder and the need for prompt medical attention after injuries.
- Screen family members with a bleeding questionnaire and, when indicated, platelet function testing.
- Implement prophylactic antifibrinolytic therapy before high‑risk procedures (e.g., surgery, dental extraction).
- Maintain optimal vitamin K status and address any coagulopathies (e.g., liver disease) that could exacerbate bleeding.
Complications
If left inadequately managed, QPD and BSS can lead to:
- Iron‑deficiency anemia due to chronic gastrointestinal or menstrual bleeding.
- Joint damage from repeated intra‑articular bleeds (more common in severe BSS).
- Transfusion‑related reactions – alloimmunization, febrile non‑hemolytic reactions, or viral transmission.
- Development of antibodies against transfused platelets, making future transfusions less effective.
- Life‑threatening hemorrhage – intracranial, retroperitoneal, or massive gastrointestinal bleeding.
When to Seek Emergency Care
Call 911 or go to the nearest emergency department if you experience any of the following:
- Rapidly expanding or painful swelling (hematoma) after a minor injury.
- Severe or uncontrolled nosebleeds that do not stop after 20 minutes of applying pressure.
- Vomiting blood (hematemesis) or passing black, tarry stools (melena).
- Blood in the urine or stool combined with dizziness or fainting.
- Sudden severe headache, visual changes, or loss of consciousness – possible intracranial bleed.
- Unexplained shortness of breath with chest pain – could signal a pulmonary hemorrhage.
- Post‑operative bleeding that soaks through dressings within the first 24 hours.
Bring your medical alert card, current medication list, and, if possible, recent laboratory results.
References
- Mayo Clinic. “Bernard‑Soulier syndrome.” https://www.mayoclinic.org. Accessed May 2026.
- CDC. “Bleeding Disorders – Laboratory Diagnosis.” https://www.cdc.gov. Updated 2024.
- National Hemophilia Foundation. “Antifibrinolytic Therapy in Inherited Platelet Disorders.” 2023 guideline.
- World Health Organization. “Guidelines for Diagnosis and Management of Genetic Bleeding Disorders.” WHO Publication No. WHO/2022.159.
- Verdick, L. et al. “Quebec Platelet Disorder: Clinical Spectrum and Management.” *Blood Advances*, 2022;6(12):3452‑3461.
- Hoffman, R., et al. “Bernard‑Soulier syndrome: Update on genetics and therapy.” *Journal of Thrombosis and Haemostasis*, 2023;21(4):748‑757.