Figure 2

3-D model of the CYP11B2 mutant with the novel missense c.977C > A mutation. The threonine residue in codon 326 is located in the I-helix of CYP11B2 protein, which is implicated in 18-hydroxylation/oxidation due to the clusters of CYP11B2 isoform-specific residues in that region. In particular, the alanine residue in position 320 is required for methyloxidase reaction and the p.Thr318Met in the I-helix is a known deleterious mutation causing aldosterone synthase deficiency. This structural information and functional correlation suggest that the I-helix region, where the novel variant c.977C > A (p.Thr326Lys) is located, is important for the enzyme activity of CYP11B2.