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

OBJECTIVE: We describe longitudinal clinical and electrophysiologic evaluation of Charcot-Marie-Tooth disease type 1A (CMT-1A) in infancy and early childhood.

BACKGROUND: The clinical picture and electrophysiologic evaluation of CMT-1A during the age of nerve conduction maturation have not been documented.

DESIGN/METHODS: 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.

RESULTS: 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.

CONCLUSION: 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.