This is a rare heritable condition, one of many with severe progressive brain degeneration (atrophy).
A small skull is evident by 2 months of age and little growth is evident thereafter. By 4 months of age infants lose their ability to visually follow objects in their environment and no longer respond with smiling and cooing. They become irritable and stiff (spasticity) and exhibit increased startle responses. Signs of seizures confirmed by an EEG are often evident by 4 months of age and progressive muscle weakness occurs, usually leading to difficulties swallowing (dysphagia) and become unable to lift their heads and move their limbs. Brain imaging reveals a decrease in brain size.
This is an autosomal recessive disorder in which normal parents (carriers with a single mutation) each contribute a single defective gene to their offspring. Such parents can expect that 1 in 4 of their children will inherit two copies and have this condition.
This disorder has been reported in four children in three Old Order Amish families in Ontario, Canada. Pediatricians and neurologists are most likely to make the diagnosis. Affected individuals are totally dependent upon their caregivers. Difficulties in swallowing may require a gastric tube for their nutrition. Infants may die in the first years of life but at least two have lived into the second decade.