Clinical Characteristics

Mutations in SMG8 gene cause congenital malformations (birth defects) involving the:


  • Global developmental delay
  • Short height
  • Microcephaly (small head)

Brain and central nervous system:

  • Intellectual disability
  • Abnormal white matter of the brain
  • Brain atrophy (loss of brain neurons and the connections between them)


  • Most commonly: ventricular and atrial septal defects (defect in the walls of the heart)

Head and Neck:

  • Malformations involving the face, including prominent nose, prominent nasolabial folds, and large ears. Additional features that were reported include depressed nasal bridge and micrognathia (small jaw).
  • Abnormalities of the eye, including strabismus (crossed eyes) and cataract

Genitourinary (present in a few reported cases):

  • Hypospadias (condition in which the opening of the penis is on the underside rather than the tip.)