Low levels of vitamin D are also frequently linked to elevations in PTH in non-dialysis CKD as indicated by early data from 3488 patients enrolled in the CKDOPPS, a prospective cohort study of patients with estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m2 from national samples of nephrology clinics in Brazil, France, Germany and the US [31]. The gene discussed is PTH; the disease is chronic kidney disease.