Mutational mechanisms in MFN2 -related neuropathy: Compound heterozygosity for recessive and semidominant mutations

Giuseppe Piscosquito, Paola Saveri, Stefania Magri, Claudia Ciano, Daniela Di Bella, Micaela Milani, Franco Taroni, Davide Pareyson

Research output: Contribution to journalArticlepeer-review

Abstract

Mitofusin-2 (MFN2) mutations are the most common cause of autosomal dominant axonal Charcot-Marie-Tooth disease (CMT, type 2A), sometimes complicated by additional features such as optic atrophy (CMT6) and upper motor neuron involvement (CMT5). Several pathogenic mutations are reported, mainly acting in a dominant fashion, although few sequence variants behaved as recessive or semidominant in rare homozygous or compound heterozygous patients. We describe a 49-year-old woman with CMT5 associated with compound heterozygosity for two MFN2 variants, one already reported missense mutation (c.748C>T, p.R250W) and a novel nonsense sequence change (c.1426C>T, p.R476∗). Her mother, carrying the p.R250W variant, had very late-onset minimal axonal neuropathy, whilst the father harboring the nonsense sequence change had neither clinical nor electrophysiological neuropathy. The missense mutation is likely pathogenic according to in silico analyses and a previous report, while the nonsense variant is predicted to behave as a null allele. The p.R250W variant behaves as semidominant by causing only a mild, almost subclinical, neuropathy when heterozygous; the nonsense mutation in the father was phenotypically silent, suggesting that haploinsufficiency for MFN2 is not disease causative, but was deleterious in the daughter who had only one active mutated MFN2 allele.

Original languageEnglish
Pages (from-to)380-386
Number of pages7
JournalJournal of the Peripheral Nervous System
Volume20
Issue number4
DOIs
Publication statusPublished - Dec 1 2015

Keywords

  • Charcot-Marie-Tooth disease
  • mitochondrial dynamic
  • mitochondrial fusion
  • mitofusin-2

ASJC Scopus subject areas

  • Clinical Neurology
  • Neuroscience(all)

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