The molecular modeling and simulation, the prediction by PolyPhen as possibly damaging, the recent suggestion that the variant may have a modifying role in deafness expression (Tang et al. 2010), and the clinical presentation with exercise intolerance in carriers of the variant are compatible with altered function of mutated Cytb, and supports a possible disease modifying role of p.C93Y. Here, MT-CYB is linked to deafness.