17p duplicated CMT 1A Characteristics of new population

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J Neurol. 2005 Mar 18

17p duplicated Charcot-Marie-Tooth 1A Characteristics of a new

population.

Marques W Jr, Freitas MR, Nascimento OJ, Oliveira AB, Calia L, Melo

A, Lucena R, Rocha V, Barreira AA.

School of Medicine of Ribeirao Preto, University of Sao o

Department of Neurology, Av. Bandeirantes, 3900 Ribeirao Preto, Sao

o, Brazil CEP 14048-900.

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.