17p duplicated Charcot–Marie–Tooth 1A

Abstract

The most frequent type of Charcot–Marie–Tooth (CMT) neuropathy is that associated with the 17p11.2–p12 chromosome duplication, whose characteristics have been well described in European and North American populations. In this study, we analyzed a Brazilian population exhibiting the mutation, found in 57 patients from 42 families (79%) of a cohort of 53 families with demyelinating CMT. Almost 20% of the duplicated cases were sporadic. In 77% of the duplicated families the mutation event occurred in the hot spot area of the CMT1A–Rep region. Forty–five percent of patients were females, 84% were Caucasians and 13% of African descent. Distal limb weakness was the most frequent abnormality, appearing in 84% of patients, although uncommon manifestations such as severe proximal weakness, floppy baby syndrome, diaphragmatic weakness and severe scoliosis were also observed. One patient was wheelchair–bound, and three suffered severe hand weakness. Sensory abnormalities were detected in 84% of the cases, but 80% were unaware of this impairment. Twelve patients complained of positive sensory manifestations such as pain and paresthesias. Progression was reported by 40%. Motor conduction velocities in the upper limbs were always less than 35 m/s, and less than 30.4 m/s in the peroneal nerve. The findings of this study expand the clinical spectrum of the disease.