Spastic Paraplegia, Optic Atrophy, and Neuropathy
Patient Information
Characteristics
Background and History
This is a hereditary progressive condition of the nervous system described in a large consanguineous kinship in Brazil
Clinical Correlations
Atrophy (degeneration) of the optic nerves may be seen at birth and is associated with poor vision later. Infants have an exaggerated startle response and the muscles are stiff with brisk reflexes (spasticity). This hyperactivity of the muscles is progressive and by the middle of the teenage years patients are confined to wheelchairs and contractures of the joints occur. Abnormal spinal curvature (scoliosis) is often seen. In the third decade slurred speech becomes noticeable. Sensory nerves are also affected.
Genetics
Inheritance
This an autosomal recessive condition in which both members of a specific pair of genes are changed (mutated). Those who carry a single change are clinically normal. However, if two parents with a single copy of the mutation have children, they can expect statistically that 1 in 4 will inherit both copies and manifest this disorder.
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
The diagnosis is most likely made by a pediatric neurologist with the collaboration of an eye doctor. No treatment is known and the impact on longevity has not been described. Physical and speech therapy might be beneficial.
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