A 5-month-old infant has rapidly increasing head circumference (+3 cm in 1 month), bulging anterior fontanelle, and sunsetting sign. MRI shows obstructive hydrocephalus with aqueduct stenosis. Which genetic condition has X-linked recessive inheritance and aqueductal stenosis as its primary feature causing congenital hydrocephalus?
- A L1 syndrome (LICAM gene mutation) ✓
- B Dandy-Walker malformation
- C Chiari type II malformation
- D Tuberous sclerosis complex
Explanation
L1 syndrome is caused by mutations in the L1CAM gene on the X chromosome (Xq28) encoding the L1 cell adhesion molecule. It is the most common genetic cause of X-linked hydrocephalus and classically presents with congenital aqueductal stenosis, adducted thumbs (cortical thumb), spastic paraplegia, intellectual disability, and aphasia (HSAS — hydrocephalus with stenosis of the aqueduct of Sylvius). The aqueductal stenosis leads to progressive obstructive hydrocephalus. Dandy-Walker malformation involves cerebellar vermis aplasia and posterior fossa cyst. Chiari II is associated with myelomeningocele. L1 syndrome is important to recognize as it has genetic counseling implications for families.
Reference: Ghai Essential Pediatrics, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.