Management of Simpson-Golabi-Behmel Syndrome
The management of Simpson-Golabi-Behmel syndrome (SGBS) requires a multidisciplinary approach with regular surveillance for associated complications, particularly tumor screening for Wilms tumor and hepatoblastoma, along with supportive care for various organ system manifestations.
Clinical Features and Diagnosis
SGBS is an X-linked overgrowth syndrome characterized by:
Pre- and postnatal macrosomia (overgrowth)
Distinctive craniofacial features:
- Macrocephaly
- Coarse facial features
- Macrostomia (large mouth)
- Macroglossia (large tongue)
- Hypertelorism (widely spaced eyes)
Other common features:
- Supernumerary nipples
- Diastasis recti/umbilical hernia
- Congenital heart defects
- Skeletal anomalies
- Hand anomalies (large hands, polydactyly)
- Mild to severe intellectual disability (though many have normal intelligence)
- Organomegaly
Genetic Basis
- SGBS is caused by mutations or deletions in the glypican genes:
- X-linked inheritance pattern (primarily affects males, though females can be affected) 2
Management Approach
1. Multidisciplinary Team
A coordinated team should include:
- Pediatrician/Primary care physician
- Medical geneticist
- Oncologist
- Nephrologist
- Cardiologist
- Neurologist
- Orthopedic specialist
- Developmental specialist
2. Tumor Surveillance
SGBS patients have increased risk for embryonal tumors, particularly:
Recommended screening protocol:
- Abdominal ultrasound every 3-4 months until at least age 7 years 3
- This should include thorough examination of both kidneys and liver
- Consider serum alpha-fetoprotein (AFP) monitoring for hepatoblastoma risk
3. Organ System Management
Cardiovascular System
- Echocardiogram at diagnosis
- Cardiology follow-up for congenital heart defects
Renal System
- Regular renal function assessment
- Ultrasound monitoring for structural abnormalities
- Management of renal dysplasia if present
Neurological System
- Developmental assessment
- Early intervention for developmental delays
- Neuroimaging if neurological symptoms present
Skeletal System
- Orthopedic evaluation for skeletal anomalies
- Management of vertebral fusion, scoliosis, or hip dislocation if present
Gastrointestinal System
- Assessment and management of GI anomalies
- Feeding support if needed
4. Growth and Development
- Regular growth monitoring using appropriate growth charts
- Developmental assessment and early intervention services
- Educational support for those with intellectual disability
5. Genetic Counseling
- Family genetic counseling
- Carrier testing for female relatives
- Prenatal diagnosis options for future pregnancies
Prognosis
The clinical spectrum of SGBS is broad:
- Mild forms with normal intelligence and good prognosis
- Severe forms with multiple congenital anomalies and early mortality
- Infantile lethal variant associated with hydrops fetalis 4
Special Considerations
- Female carriers: While SGBS is X-linked, affected females have been reported and may require similar management approaches 2
- Cancer risk: Ongoing surveillance is critical as tumor development can occur throughout childhood
- Severity spectrum: Management should be tailored to the severity of presentation, which can range from mild to lethal 4, 5
Follow-up Care
- Regular follow-up with multidisciplinary team
- Ongoing developmental assessment
- Continued tumor surveillance throughout childhood
- Transition planning to adult care for adolescents
The management of SGBS requires vigilant monitoring for complications, particularly tumors, while providing supportive care for the various manifestations of this complex syndrome.