A reduction in levels of the nucleo-skeletal protein Lamin B1 is a highly reliable marker of cellular senescence of multiple cell types,44 accompanying physiological cellular ageing45 and particularly pronounced in some premature ageing syndromes, such as the laminopathy Hutchinson Guilford Progeria Syndrome (HGPS).46, 47, 48 We therefore stained the same fresh PBMCs with a Lamin B1-specific antibody. The gene discussed is LMNB1; the disease is premature aging syndrome.