Understanding Hemophilia
Hemophilia is caused by mutations in genes that provide instructions for making clotting factors. These proteins work together in a complex cascade to form blood clots. When one factor is missing or deficient, the clotting process is disrupted.
Types of Hemophilia
- Hemophilia A (Classic Hemophilia):
- Factor VIII deficiency
- 80-85% of cases
- 1 in 5,000 male births
- Hemophilia B (Christmas Disease):
- Factor IX deficiency
- 15-20% of cases
- 1 in 25,000 male births
- Hemophilia C:
- Factor XI deficiency
- Rare, milder form
- Not X-linked (affects both sexes)
Severity Classification
- Severe: <1% normal factor activity
- Spontaneous bleeding episodes
- Frequent joint/muscle bleeds
- Moderate: 1-5% normal factor activity
- Occasional spontaneous bleeds
- Prolonged bleeding after trauma
- Mild: 5-40% normal factor activity
- Bleeding mainly after surgery/trauma
- May go undiagnosed until adulthood
Inheritance Pattern
X-Linked Recessive Inheritance
Hemophilia A and B are inherited in an X-linked recessive pattern. The genes for factors VIII and IX are located on the X chromosome.
For Males (XY):
- One altered X chromosome causes hemophilia
- Affected males cannot pass to sons
- All daughters will be carriers
- 30% of cases are new mutations
For Females (XX):
- Usually carriers with one affected X
- May have mild symptoms (lyonization)
- 50% chance of passing to each child
- Rare to have hemophilia (requires two affected X chromosomes)
Genetic Counseling
- Important for family planning
- Carrier testing available
- Prenatal diagnosis possible
- Preimplantation genetic diagnosis option
Signs and Symptoms
Common Bleeding Manifestations
- Joint bleeds (hemarthrosis):
- Most common in severe hemophilia
- Knees, elbows, ankles most affected
- Warmth, swelling, pain
- Limited range of motion
- Muscle bleeds:
- Deep muscle hematomas
- Iliopsoas bleeds particularly serious
- Can compress nerves
- Easy bruising:
- Large, deep bruises
- From minor bumps
- Prolonged bleeding:
- After cuts, dental work, surgery
- May restart days later
Serious Bleeding Complications
- Intracranial hemorrhage:
- Life-threatening emergency
- Can occur spontaneously or after minor head trauma
- Leading cause of death
- Gastrointestinal bleeding:
- Blood in stool
- Black, tarry stools
- Hematuria:
- Blood in urine
- Usually painless
- Retroperitoneal bleeding:
- Back/flank pain
- Can be life-threatening
Age-Related Presentations
Newborns:
- Bleeding after circumcision
- Intracranial hemorrhage (2-4%)
- Cephalohematoma
- Prolonged bleeding from heel sticks
Toddlers:
- Increased bruising when learning to walk
- Oral bleeding from falls
- First joint bleeds
Children/Adults:
- Recurrent joint bleeds
- Chronic arthropathy
- Muscle hemorrhages
Diagnosis
Clinical Suspicion
- Family history of bleeding
- Excessive bleeding in males
- Unexplained bruising/bleeding
- Joint swelling in children
Laboratory Tests
Screening Tests:
- PT (Prothrombin Time): Normal
- aPTT (activated Partial Thromboplastin Time): Prolonged
- Platelet count: Normal
- Bleeding time: Normal
Specific Factor Assays:
- Factor VIII activity level
- Factor IX activity level
- Confirms diagnosis and severity
- Distinguishes hemophilia A from B
Additional Tests:
- Von Willebrand factor testing
- Inhibitor screening
- Genetic testing
- Carrier testing for females
Prenatal Diagnosis
- Chorionic villus sampling (10-12 weeks)
- Amniocentesis (15-20 weeks)
- Fetal blood sampling (18+ weeks)
- Non-invasive prenatal testing emerging
Treatment
Factor Replacement Therapy
The cornerstone of hemophilia treatment is replacing the missing clotting factor.
Types of Factor Products:
- Plasma-derived factors:
- From donated human plasma
- Viral inactivation processes
- Contains other proteins
- Recombinant factors:
- Genetically engineered
- No human/animal proteins
- Reduced infection risk
- Standard half-life or extended half-life
Treatment Approaches:
- On-demand treatment:
- Given at time of bleeding
- For mild/moderate hemophilia
- Prophylaxis:
- Regular infusions to prevent bleeds
- Standard for severe hemophilia
- Usually 2-3 times per week
- Extended half-life products allow less frequent dosing
Non-Factor Therapies
Emicizumab (Hemlibra):
- Bispecific antibody for Hemophilia A
- Mimics factor VIII function
- Subcutaneous injection
- Weekly to monthly dosing
- Works with inhibitors
Desmopressin (DDAVP):
- For mild Hemophilia A only
- Releases stored factor VIII
- Temporary effect
- Cannot use repeatedly
Antifibrinolytic Agents:
- Tranexamic acid
- Aminocaproic acid
- For mucosal bleeding
- Dental procedures
Gene Therapy
- FDA-approved for Hemophilia A and B
- Single infusion of modified virus
- Delivers functional gene to liver
- Can achieve normal factor levels
- Long-term durability being studied
- High cost but potentially curative
Managing Inhibitors
20-30% of severe Hemophilia A patients develop inhibitors (antibodies against factor VIII).
- Bypassing agents:
- Activated prothrombin complex concentrate
- Recombinant factor VIIa
- Immune tolerance induction:
- High-dose factor exposure
- Can eliminate inhibitors
- Emicizumab: Effective with inhibitors
Comprehensive Care
Hemophilia Treatment Centers
- Multidisciplinary team approach
- Hematologists
- Specialized nurses
- Physical therapists
- Social workers
- Genetic counselors
Home Treatment
- Self-infusion training
- Factor storage and handling
- Venous access devices if needed
- Treatment logs
- Emergency supplies
Physical Therapy
- Maintain joint function
- Strengthen muscles
- Prevent contractures
- Improve balance and proprioception
- Aquatic therapy beneficial
Pain Management
- Acetaminophen preferred
- Avoid NSAIDs (affect platelets)
- Ice for acute bleeds
- Physical therapy
- COX-2 inhibitors with caution
Living with Hemophilia
Activity Guidelines
- Recommended activities:
- Swimming
- Walking/hiking
- Cycling with helmet
- Golf
- Table tennis
- Avoid high-contact sports:
- Football
- Hockey
- Boxing
- Wrestling
- With precautions:
- Basketball
- Soccer
- Baseball
Travel Considerations
- Carry factor and supplies
- Letter from physician
- Know nearest treatment centers
- Travel insurance coverage
- Factor storage requirements
Dental Care
- Preventive care crucial
- Inform dentist of hemophilia
- Factor coverage for procedures
- Antifibrinolytics for extractions
- Avoid nerve blocks if possible
Surgery Preparation
- Coordinate with hemophilia team
- Factor levels 80-100% for surgery
- Maintain levels postoperatively
- Monitor for inhibitors
- Physical therapy planning
School/Work
- Educate teachers/employers
- Emergency action plan
- Factor storage if needed
- Activity modifications
- Know rights under disability laws
Complications
Joint Disease (Hemophilic Arthropathy)
- Most common long-term complication
- Repeated bleeds damage cartilage
- Progressive joint destruction
- Chronic pain and disability
- May require joint replacement
Inhibitor Development
- 20-30% in severe Hemophilia A
- 3-5% in Hemophilia B
- Usually within first 50 exposures
- Makes treatment challenging
- Risk factors include:
- Severe mutations
- Family history
- Intensive treatment
Viral Infections (Historical)
- HIV/AIDS in 1980s
- Hepatitis C before 1992
- Current products very safe
- Screening and viral inactivation
Pseudotumors
- Encapsulated hematomas
- Can erode bone
- Require surgical removal
- Rare with prophylaxis
Prognosis
Modern Outlook
- Near-normal life expectancy with treatment
- Prophylaxis prevents most complications
- Quality of life dramatically improved
- Most can participate in normal activities
- Career options less limited
Factors Affecting Prognosis
- Access to treatment: Critical factor
- Prophylaxis adherence: Prevents joint damage
- Inhibitor development: Complicates treatment
- Early diagnosis: Better outcomes
- Comprehensive care: Reduces complications
Future Directions
- Gene therapy offering potential cure
- Longer-acting factors
- Non-factor therapies expanding
- Improved inhibitor management
- Better joint preservation strategies