SNP Shot: Genomic Insights

Troyer syndrome falls under the umbrella of hereditary spastic paraplegias (HSPs), a collection of inherited diseases distinguished by a gradual stiffening (spasticity) of the legs that can progress to paralysis (paraplegia). HSPs are generally classified as either pure or complex. Pure HSPs mainly affect the legs. However, Troyer syndrome, a complex form, affects the legs and may also involve the arms (usually to a lesser extent), brain structure or its functions, and the peripheral nervous system (the network that links the brain and spinal cord to muscles and sensory organs).

Individuals with Troyer syndrome can experience a range of symptoms. Common signs and symptoms include leg muscle spasticity, increasing muscle weakness, paraplegia, muscle atrophy in the hands and feet (distal amyotrophy), short stature, developmental delays, learning disabilities, difficulties in speaking (dysarthria), and mood disorders. Additional potential indicators encompass heightened reflexes in the legs (hyperreflexia), involuntary limb movements (choreoathetosis), skeletal abnormalities, and knock-knees (valgus deformity).

A hallmark of Troyer syndrome is the slow, continuous breakdown and loss of muscle cells and motor neurons (specialized nerve cells that control muscle movement) throughout an individual's life. This process results in a gradual decline in both muscle and nerve function. The degree of disability caused by Troyer syndrome increases with age, frequently leading to the need for wheelchair assistance by the time an individual reaches their 40s or 50s.

Inheritance:

Troyer syndrome is inherited in an autosomal recessive manner. To develop the syndrome, a person must inherit two copies of a mutated gene, one from each parent. The parents, who each carry a single copy of the mutated gene, are typically unaffected carriers and do not exhibit any symptoms of the condition.