Gene dosage is a mechanism for Charcot-Marie-Tooth disease type 1A.

Charcot-Marie-Tooth disease type 1A (CMT1A) is the most common inherited peripheral neuropathy in humans, characterized electrophysiologically by decreased nerve conduction velocities (NCVs). CMT1A is associated with a large submicroscopic DNA duplication in proximal 17p. In this report we demonstrate that a patient with a cytogenetically visible duplication, dup(17)(p11.2p12), has decreased NCV. Molecular analysis demonstrated this patient was duplicated for all the DNA markers duplicated in CMT1A as well as markers both proximal and distal to the CMT1A duplication. These data support the hypothesis that the CMT1A phenotype can result from a gene dosage effect.