Definition

Hereditary spastic paraplegia (HSP) is a hereditary degenerative disorder affecting the corticospinal tracts (long never fibers that supply the upper and lower limbs) within the spinal cord. The disease frequently results in progressive spasticity (involuntary movement) of leg muscles with varying degrees of stiffness and weakness of other muscle groups in the thighs, lumbar spinal area, and muscles responsible for up and down feet movements. The extent of degeneration and severity of symptoms varies among the affected people, even those among the same family group. The age of onset for the disease also varies. Some families show a pattern of disease, with symptoms developing earlier in each new generation. In most individuals, however, the disease onset occurs between the second and the fourth decades of life, with a few cases...