Hereditary cerebellar ataxias can be divided into two main categories as early onset and late onset. The early onset group consists of Friedreich's Ataxia (FA) and early Onset Cerebellar Ataxia (EOCA). EOCA is distinguished from FA in terms of retained reflexes. In comparison to FA, in EOCA, upper limb ataxia and loss of joint position sense are less severe, and optic atrophy, scoliosis, cardiomyopathy, diabetes mellitus are less common. Additionally, severe sensory neuropathy in electrophysiologic study is specific to FA.

Characteristics that fitted both to FA and EOCA were seen in the clinical and laboratory researches of a 14-year-old patient. Though absence of sensory potentials reminded of FA, presence of retained reflexes was reminding EOCA. Therefore, genetic research was essential to make a certain diagnosis of the patient whose clinical diagnosis gave contradictory clues.