The characteristic symptom of Costeff syndrome is the onset of progressively worsening eyesight caused by degeneration of the optic nerve (optic atrophy) within the first few years of childhood, with the majority of affected individuals also developing motor disabilities later in childhood.
Costeff syndrome is characterized by a progressive loss of vision caused by degeneration of the optic nerve, which typically begins in early childhood and may be accompanied by motor impairments that develop later on.