MAX and adrenal gland pheochromocytoma: In addition, somatic mutations of RET, VHL, NF1, MAX, HIF2A and HRAS can be detected in a further 25–30% of these tumors.[3–6] SDHx and VHL-related PCC/PGL are referred to as ‘cluster 1’ tumors, following microarray gene expression studies, while ‘cluster 2’ includes the tumors with RET, NF1, TMEM127, and MAX mutations.[7,8]