Hereditary Hypercalcemia Caused by a Homozygous Pathogenic Variant in the CYP24A1 Gene: A Case Report and Review of the Literature

Figure 2

LC-MS/MS chromatogram of dihydroxylated vitamin D metabolites. Serum samples were prepared by immunoextraction and derivatized with DMEQ-TAD. Peaks corresponding to 6S and 6R isomers of DMEQ-TAD adducts of 24,25(OH)₂D₃ and 1,25(OH)₂D₃ were observed using the multiple reaction monitoring (MRM) transition of mass/charge (m/z) 762.3- ->468.1+484.1, from which serum concentrations of these metabolites were determined. The figure reveals the dramatically reduced concentration of 24,25(OH)₂D₃ in the proband II.3 as well as elevated 1,25(OH)₂D₃, in comparison to unaffected family members.