Table 2.

Diagnostic Criteria Proposed by Harding in 1981¹⁴

Primary (must be present) onset before 25 years progressive ataxia of limbs and gait absence of knee and ankle jerks

Secondary dysarthria extensor plantar responses

If secondary criteria are absent, the following have to be present: (1) an affected sib fulfilling primary and secondary criteria, (2) median motor nerve conduction velocities of greater than 40 m/s, thus excluding cases of type 1 hereditary motor and sensory neuropathy.