Thus, a VMR over the threshold >25 (Figs. 4B and 5) is a sensitive indicator of vitamin D deficiency and could be a very useful additional parameter for the pediatrician/clinician using serum 25‐OH‐D <12 ng/mL and a PTH assay to assess vitamin D deficiency.(41, 42) In CKD, the pathogenesis involved is different, suggesting a gradual loss or downregulation of 24‐hydroxylation of 25‐OH‐D3,(72) but the consequence is the same and the 25‐OH‐D3/24,25‐(OH)2D3 VMR often rises to an even greater degree than in simple vitamin D deficiency. The gene discussed is PTH; the disease is vitamin D deficiency.