In addition to the dMMR case PD56546c, two other cases harboured 2 KMT2D loss-of-function (LoF) mutations each; PD56526a, a lung metastasis with p.R3082Gfs*15 (c.9244_9245del) and p.C778* (c.2334 C > A), and PD56542c, a primary tumour with p.C1408S (c.4222 T > A; located within a PHD-finger and predicted to be deleterious with a SIFT score of 0) and p.F600Cfs*322 (c.1797_1821del; Fig. 1, Supplementary Fig. 7 and Supplementary Data 2), which strongly suggests that biallelic inactivation of KMT2D may be a mechanism of tumourigenesis and/or progression in BCAC. The gene discussed is KMT2D; the disease is neoplasm.