spastic paraplegia 18 is an autosomal recessive disorder characterized by motor dysfunction, joint contracture and mental retardation. we describe two families as three cases. case 1 is a 35-year-old woman with and spasticity and mild weakness in lower limbs. case 2 and 3 are a sister and brother aged six and two respectively. the older sister suffered from lower limb spasticity, equinovarus an...