Mutations in SMG9 gene cause congenital malformations (birth defects) involving the:
– Brain and central nervous system:
- Dandy-Walker malformation (affects the part of the brain which coordinates movements and may cause build up of fluid in the brain; intellectual disabilities and delayed development are also common)
- Brain atrophy (loss of brain neurons and the connections between them)
- Stiffness or floppy limbs that become stiff as the disease progresses
– Heart:
- Ventricular septal defect (defect in the walls of the heart)
- Underdevelopment of the valves of the heart
– Head and Neck:
- Malformations involving the face, including microphthalmia (abnormally small eyes), hypertelorism (increased distance between the eyes), broad or depressed nasal bridge, cleft lip, and cleft palate.
– Skeletal:
- Hand and foot malformations