Somatosensory evoked potentials correlate with genetics in Huntington's disease.

Abnormalities of somatosensory evoked potentials (SEPs) have been reported in Huntington's disease, a neuropsychiatric disorder caused by the expansion of a CAG trinucleotide repeat. The aim of our study was to determine the relationship between these electrophysiological changes and the length of the nucleotide repeat. We found a striking correlation between the decrease in the early component amplitudes (N20 and N30) of the median nerve SEP and the repeat length, suggesting that these SEP alterations are indeed related to the genetically determined pathological process. The cortical components of the tibial nerve SEP exhibited a dramatic alteration in the patient group and were the only SEP changes found in the group of asymptomatic carriers of the mutation, being more sensitive than the median nerve SEPs.