Charcot-Marie-Tooth disease type 1A with 17p duplication in infancy and early childhood: a longitudinal clinical and electrophysiologic study.

We describe longitudinal clinical and electrophysiologic evaluation of Charcot-Marie-Tooth disease type 1A (CMT-1A) in infancy and early childhood. The clinical picture and electrophysiologic evaluation of CMT-1A during the age of nerve conduction maturation have not been documented. Twenty at-risk children from six unrelated CMT-1A families were examined in the first 5 years of life. Initial ages were 1 month to 4 years (mean, 1.5 years) and final ages 4 to 19 years (mean, 9 years). All subjects had two or more motor and sensory conduction velocities (MCV and SCV), corrected distal motor latencies (DML), and F-waves. Twelve children were affected. Initially, two of these (17%) had symptoms, whereas five (42%) were symptomatic at the end. Numbers of abnormal examinations at the beginning was six (50%) and at conclusion was 10 (83%). None of the patients were disabled. From 2 years of age, all affected children had abnormal MCV, SVC, F-waves, and DML. Prolonged DML was already present in the first months of life and preceded slowing of MCV in three cases. The electrophysiologic studies were concordant with the presence or absence of the CMT-1A DNA duplication. In most CMT-1A patients, symptoms appear in early childhood, although the florid clinical picture does not occur until the second decade of life. Serial electrophysiologic studies can detect the CMT-1A gene carrier in infancy.