sentence: Interestingly , amongst the top two most frequently altered enzyme families in SCCHN were the NSD ( nuclear SET-Suppressor of variegation 3-9 , Enhancer of zeste and Trithorax-domain , NSD1 , NSD2 / WHSC1 / MMSET , NSD3 / WHSC1L1 ) family of protein lysine methyltransferases ( PKMTs ) which are genetically altered in 28 % of SCCHN , implying a critical role for these enzymes in SCCHN oncogenesis [ 3 , 4 ] .