The subgroup T1 included tumours that were mainly wild-type for the commonly mutated genes ATRX, DAXX and MEN1. This subgroup presented tumours with heterogeneous patterns of copy number alteration, agreeing with Chan et al.4 who reported gene expression and methylation profiles to be more homogenous in mutant ATRX/DAXX/MEN1 tumours than in wild-type tumours. The gene discussed is ATRX; the disease is neoplasm.