Last updated 15d ago
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A 2-year-old has macrocephaly, accelerated linear growth (above 97th percentile), and developmental delay with advanced bone age. Facial features include a prominent forehead, downslanting palpebral fissures, and a pointed chin. Parents report the child was large at birth.
- Recurrent microdeletion: 5q35 (~1.9 Mb including NSD1 gene)
- Also caused by NSD1 point variants (~50% of cases)
- ~95% de novo
- Inheritance: AD
- Overgrowth: prenatal onset, tall stature, macrocephaly
- Advanced bone age
- Characteristic facies: prominent forehead, frontal bossing, downslanting palpebral fissures, pointed chin
- Intellectual disability (usually mild to moderate)
- Behavioral issues
- Neonatal hypotonia, poor feeding
- Increased risk for tumors (neuroblastoma, Wilms tumor, leukemia) - mild elevation
- Cardiac defects, renal anomalies, scoliosis possible
- Temporal balding pattern
- CMA for 5q35 deletion
- NSD1 sequencing if CMA negative but clinical suspicion high
- Skeletal survey shows advanced bone age
- Developmental support
- Consider tumor surveillance (individualized based on family history)
- Monitor growth, cardiac, and renal function
SOTTT♥SSSSSS:
- Serebral gigantism
- Overgrowth (vs undergrowth for most other microdeletions)
- Tinkle (renal anomalies)
- Tall stature
- Tumors (mild increased risk)
- Toupee (baldness)
- ♥ = Cardiac defects
- Scoliosis
- Seizures
- SET domain protein NSD1
- 5q35 (NSD1 locus - "5" looks like an "S")
