Cerebral Atrophy, Autosomal Recessive
Patient Information
Characteristics
Background and History
This is a rare heritable condition, one of many with severe progressive brain degeneration (atrophy).
Clinical Correlations
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.
Genetics
Inheritance
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.
Pedigree
Autosomal recessive
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.
Diagnosis and Prognosis
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.
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