Clinical and Genetic Characteristics in Patients of Charcot-Marie-Tooth type 2A with Mitofusin 2 (MFN2) Mutations

ABSTRACT

BACKGROUND: Mitofusin 2 (MFN2) is a membrane protein and is an essential component of mitochondrial fusion machinery. Mitochondrial fusion is essential for various biological functions in mammalian cells. Thus mutations in MFN2 are the underlying cause of Charcot-Marie-Tooth neuropathy type 2A (CMT2A). However, there has been no reports investigating the MFN2 genes in Korean CMT patients. Therefore, we investigated to find the clinical and genetic characteristics in Korean patients with the MFN2 gene mutation. METHODS: We examined the mutations of the MFN2 gene in 137 Korean CMT families. According to criteria from the European CMT consortium, CMT2 was 45 families. Mutations were confirmed by both strands sequencing. Nerve conduction studies were carried out in CMT patients having each mutation. RESULTS: Eight pathogenic mutations were found in 10 families. Six mutations (Leu92Pro, Gly127Asp, His165Arg, Ser263Pro, Arg364Trp, Met376Thr) were determined to be novel, and those were not detected in the 100 healthy controls. A de novo missense mutation was found in three CMT families (30%). The frequency of the MFN2 mutation was 22.2%, which was higher than those found in the Cx32 mutation. In CMT2A, the frequencies with early age at onset (<10 years) and flat feet were 46.2%. CONCLUSIONS: We found MFN2 mutations in patients with sporadic or dominantly inherited CMT. In the majority of cases with CMT type 2, the axonal neuropathy, may be due to MFN2 mutations.