It was with great interest that I read Casasnovas et al article "Phenotypic Spectrum of MFN2 Mutations in the Spanish Population". The authors mention the Gly298Arg mutation in one of their families, with 2 affected individuals, and state that this has previously been described. They refer to Lawson's 2005 article (Ref#10, Lawson VH, Graham BV, Flanigan KM. Clinical and electrophysiologic features of CMT2A with mutations in the mitofusin 2 gene. Neurology 2005;65:197) as having described this mutation previously.

However, upon careful review of Lawson's article, I only found mention of this mutation as a SNP found by the Utah researchers in 3% of their control chromosomes.

Would the authors please comment on what evidence they have that this is a disease causing mutation, or is this a benign polymorphism? As the authors mention, this point mutation is in a highly conserved region of the dynamin like GTPase region of mitofusin 2, and results in a non- synonymous amino acid change, therefore one would suspect it as disease causing.

Conflict of Interest:

None declared