Normal human ageing is a complicated biological phenomenon. 'Werner's syndrome (WS)', caused by mutations of RecQ type DNA helicase, has been recognized as a top ranking 'segmental' progeroid syndrome. Patients with WS show a wide variety of clinical and biological manifestations in the four major self-assembly body systems (nervous, immune, connective tissue and endocrine-metabolic systems) similar to normal ageing at an early stage of their life, followed by death at an average age of 46. The sequential appearance of clinical and biological deterioration of the body systems observed in WS suggested that the disorder is more than a segmental progeroid syndrome, analysis of which may shed new light on the question 'Why and how we age?'