Somatic whole-genome sequencing of CCS skin tumours confirms loss of CYLD heterozygosity and demonstrates additional mutations in the tumour suppressors DNMT3A and BCOR in up to a third of benign CCS tumours, and in TP53 and MBD4 in some malignant CCS tumours (Davies et al., 2019). The gene discussed is CYLD; the disease is neoplasm.