SDHA and gastrointestinal stromal tumor: To unravel the mitochondrial role in concurrent GIST and NB, we assessed SDHA expression in recurrent tumor tissues and adjacent ones, revealing stark SDHA loss in tumors alongside up-regulated subunits of mitochondrial complex I (ND5), complex III (UQCRC2), complex IV (CO1), and complex V (ATP5a) (Fig. 1G (1)).