Fig. 2.

DNA sequence analysis of mutation in CYP2R1 vitamin D 25-hydroxylase. The partial DNA sequence of exon 2 from the CYP2R1 gene is shown from a normal individual (Upper) and from an individual with selective 25-hydroxyvitamin D deficiency (Lower). The codon specifying amino acid 99 is CTT in the normal gene and CCT (arrow) in the affected individual. The T → C transition mutation in the second nucleotide causes a change from leucine to proline at residue 99. All other nucleotides in the CYP2R1 gene of the proband were identical to those in normal individuals.