In this study, the expression pattern profiles of NDUFA4, one of the nDNA-encoded subunits of complex IV, and 16 mitochondrial complex I subunits, including 7 mtDNA and 9 nDNA-encoded subunits, were analyzed in FRDA patients in order to determine whether the complex I genes were expressed through co-regulation or through sub-clustering. This evidence concerns the gene COXFA4 and Friedreich ataxia.