Mitochondrial DNA variations and evidence of haplogroups in Indian Friedreich's ataxia (FRDA) patients. I. Mudila, F. Mohammed, A. Srivastava; Journal of the Neurological Sciences, Volume 333, Supplement 1, 15 October 2013, Pages e708-e709. http://dx.doi.org/10.1016/j.jns.2013.07.2446
Variations at positions 16 519, 4883 and 5178 suggest that these variations may act as modifier for the disease.