FGF-23 signalling requires the presence of the coreceptor Klotho.S40 CKD is characterised by Klotho deficiency and increased FGF-23 levels, which are independently associated with cardiovascular mortality.S41 In mouse models of Klotho deficiency, an accelerated ageing syndrome results with vascular calcification that resembles features of uraemia.S42. The gene discussed is KL; the disease is chronic kidney disease.