Late onset autosomal dominant Charcot–Marie–Tooth 2 neuropathy in a Costa Rican family

Abstract

Objective: To describe the clinical, electrophysiologic and morphologic features of a Costa Rican family with an autosomal dominant inherited Charcot–Marie–Tooth (CMT) neuropathy.

Methods: The field study took place in Costa Rica, Central America. Seven patients underwent neurological examinations and standard electrodiagnostic tests, and a sural nerve biopsy was taken from one patient. Fifteen family members were screened for gene defects associated with CMT disease.

Results: Characteristic features of this family were a late age of onset (35–56 years), positive sensory symptoms and muscle cramps. Based on electrodiagnostic and morphologic data, the patients were classified as having a CMT2 neuropathy. The CMT1A duplication/HNPP deletion and point mutations in genes PMP22, MPZ, C×32 and EGR2 implicated in the most common types of CMT disease were excluded. Subsequently, almost all known CMT loci were excluded by linkage analysis.

Discussion: Features of this family were a late age of onset and positive sensory symptoms. This new autosomal dominant CMT neuropathy is associated with an unknown gene defect.

Keywords:

• AUTOSOMAL DOMINANT
• AXONAL
• CMT2
• HEREDITARY NEUROPATHY
• LATE DISEASE ONSET