FBXW7 and neoplasm: Loss of heterozygosity at FBXW7 is observed infrequently, especially for WD40 propellor tip mutations, and few tumours carry biallelic FBXW7 mutations predicted to abolish protein function.13, 15 These data suggest that FBXW7 does not function as a standard tumour suppressor gene through the two hit mechanism of inactivation,16 and partial loss of FBXW7 function may be sufficient to cause tumorigenesis.