Intellectual Disability in Children: Sanfilippo Syndrome

Overview

Sanfilippo syndrome, also known as mucopolysaccharidosis type III, is a rare genetic disorder that affects metabolism and brain development, primarily in children. It is considered a lysosomal storage disease because it involves the buildup of heparan sulfate in cells due to the lack of a key enzyme.

• Prevalence: Affects 1 in 70,000 births in the U.S.
• Life Expectancy: Generally 10-20 years, varying by type.
• Genetics: Increased risk with family history.

Types of Sanfilippo Syndrome

1. Type A:

   • Most common and severe.
   • Rapid progression with early loss of walking and talking abilities.
   • Average lifespan is around 15 years.

2. Type B:

   • Less common, slower progression than Type A.
   • Average lifespan is about 19 years.

3. Types C and D:

   • Least common, with Type D being the rarest.
   • Slower progression than Types A and B.
   • Type C lifespan is about 23 years; Type D lifespan is unclear due to rarity.

Symptoms

Early Symptoms (birth to age 2)

• Breathing problems.
• Coarse facial features (prominent forehead, eyebrows, full lips and nose).
• Excessive body hair (hirsutism).
• Macrocephaly (large head).
• Persistent upper respiratory congestion.
• Chronic diarrhea.
• Hernias (umbilical or inguinal).
• Behavioral issues similar to autism.
• Speech and developmental delays.
• Frequent ear or sinus infections.
• Sleep disturbances.
• Compulsive behavior and hyperactivity.

Late Symptoms

• More pronounced facial features.
• Cognitive decline.
• Autism-like behaviors.
• Brain atrophy.
• Seizures.
• Movement issues leading to immobility.
• Chewing and swallowing problems.
• Hearing and vision loss.
• Enlarged liver or spleen.
• Early death.

Phases of Progression

1. Phase I (ages 1-3): Slowed speech and cognitive development.
2. Phase II (ages 3-4): Intensified behavioral and sleep issues, decline in learning and thinking abilities.
3. Phase III (teen years): Dementia-like symptoms, loss of movement, communication, and eating abilities.

Diagnosis

• Early Diagnosis: Challenged by symptom overlap with other conditions like autism.
• Tests:
  • Urine MPS Screening Analysis for heparan sulfate.
  • Blood enzyme activity test.

Treatment and Management

• Supportive Care: Focus on symptom management and quality of life improvement.
• Clinical Trials: Enzyme replacement therapy (ERT) and gene therapy (experimental).

Therapies

• Speech-language Therapy: To maintain communication abilities.
• Feeding Therapy: Managing chewing/swallowing difficulties.
• Physical Therapy: Maintaining mobility as long as possible.
• Occupational Therapy: Handling motor skills and sensory needs.

Prevention and Support

• Genetic Testing: For parents planning to conceive.
• Support Networks: Cure Sanfilippo Foundation and other organizations.
• Resource Access: State and federal aid, educational support, and financial assistance.

Additional Considerations

• Parental Support: Emotional support and mental health resources for caregivers.
• Community Engagement: Connecting with others in the Sanfilippo community for shared experiences and support.