Could a patient with a mother having blood type AB be at risk for von Willebrand disease?

Blood Type and Von Willebrand Disease Risk Assessment

A patient with a mother having blood type AB cannot be at risk for von Willebrand disease based on blood type alone, as von Willebrand disease is not directly linked to blood type inheritance patterns.

Understanding Von Willebrand Disease (VWD)

Von Willebrand Disease is the most common inherited bleeding disorder that affects both males and females equally 1. The condition results from defects in the von Willebrand factor (VWF) glycoprotein, which can be either quantitative (Types 1 and 3) or qualitative (Type 2) 2.

Key Facts About VWD:

• VWD is inherited in an autosomal pattern (not linked to blood type)
• It affects approximately 1 in 100 women 3
• Most common symptom in women is menorrhagia (heavy menstrual bleeding)
• 5-20% of women with menorrhagia have undiagnosed VWD 3

Diagnostic Approach for VWD

The diagnosis of VWD requires a comprehensive evaluation that includes:

1. Standardized bleeding assessment tool (BAT) to objectively quantify bleeding history 4
2. First-line laboratory tests:
   • Complete blood count (CBC) with platelet count
   • Activated partial thromboplastin time (aPTT)
   • Prothrombin time (PT)
   • VWF assays (VWF antigen, VWF activity) 4
3. Family history assessment - nearly all clinicians (98%) include this in initial bleeding assessment 5

Important Diagnostic Considerations:

• No single laboratory test can definitively screen for VWD 4
• Testing may need to be repeated up to 3 times to ensure reliable results 5
• VWF is an acute phase reactant, so levels can vary in response to clinical status 5

Blood Type and VWD Relationship

While blood type does influence VWF levels, it is not a determinant of VWD inheritance:

• People with blood type O have approximately 25% less VWF than those with non-O blood groups 6
• Despite this association, ABO blood group-specific reference ranges are not recommended for VWD diagnosis 5
• VWD is inherited in an autosomal pattern, not linked to blood type inheritance

Clinical Implications

For a patient whose mother has blood type AB:

• The mother's blood type does not increase the patient's risk for VWD
• VWD risk should be assessed based on:
  • Personal bleeding history (using standardized BAT)
  • Family history of bleeding disorders (not just blood type)
  • Laboratory testing of VWF levels and function

Common Pitfalls to Avoid

1. Misattributing bleeding risk to blood type alone - While blood type O is associated with lower VWF levels, VWD is determined by specific genetic mutations in the VWF gene 1

2. Relying solely on a single VWF level measurement - VWF levels can fluctuate due to various factors including stress, inflammation, pregnancy, and hormonal status 4

3. Overlooking other causes of bleeding symptoms - Consider other conditions like platelet disorders, hypermobility syndromes (assessed in only 55% of patients), or iron deficiency (which should be routinely checked) 5

4. Failing to consult with a hematologist - Patients with suspected bleeding disorders should be referred to a hemophilia treatment center or hematologist with expertise in bleeding disorders for definitive diagnosis 3

In conclusion, a patient's risk for VWD is not determined by their mother's blood type AB, but rather by specific genetic mutations affecting VWF quantity or function that should be evaluated through appropriate clinical and laboratory assessment.