CLINICAL VARIABILITY IN 2 PAIRS OF IDENTICAL-TWINS WITH THE CHAREOT-MARIE-TOOTH DISEASE TYPE 1A DUPLICATION

We report two pairs of male homozygotic twins in two unrelated familie s with the Charcot-Marie-Tooth disease type 1A duplication. Homozygosi ty was supported by DNA analysis. There was remarkable congruity of co nduction velocities between the left and right side of each twin and b etween twin brothers. The similarity and symmetry of the electrophysio logic deficit contrast with the variable and asymmetric clinical prese ntations. Variability of clinical expression in these patients with id entical mutations suggests the action of stochastic factors or environ mental modulation of disease severity.