Molecular Basis of Aromatase Deficiency in a 46, XX Patient with Mutation of Arginine 550 to Tryptophan in <em>POR</em>: Expanding the Endocrine Phenotype in PORD

• DOI: 10.20944/preprints201909.0103.v1
• Publication Date: 2019-09-10T00:05:19Z
• Authors: Shaheena Parween; Mónica Fernández ...; Sara Benito-Sanz; Núria Camats; Maria Natalia Roj...; Juan-Pedro López-...; Sameer S Udhane; Norio Kagawa; Christa Flück; Laura Audì; Amit Pandey
• Keywords: 03 medical and health sciences; 0302 clinical medicine; endocrinology_metabolomics; 3. Good health

Context: Mutations in Cytochrome P450 oxidoreductase (POR) cause a form of congenital adrenal hyperplasia (CAH). We are reporting a novel R550W mutation in POR identified in a 46, XX patient with signs of aromatase deficiency. Objective: Analysis of aromatase deficiency from R550W mutation in POR. Design, Setting, and Patient: Both the child and the mother had signs of virilization. Ultrasound revealed the presence of uterus and ovaries. No defects in CYP19A1 were found, but further analysis with a targeted Disorders of Sexual Development NGS panel (DSDSeq.V1, 111 genes) on a NextSeq (Illumina) platform in Madrid and Barcelona, Spain, revealed compound heterozygous mutations c.73_74delCT/p.L25FfsTer93 and c.1648C&gt;T/p.R550W in POR. WT and R550W POR were produced as recombinant proteins and tested with multiple cytochrome P450 enzymes at University Children&rsquo;s Hospital, Bern, Switzerland. Main Outcome Measure and Results: R550W POR showed 41% of the WT activity in cytochrome c and 7.7% activity for reduction of MTT. Assays of CYP19A1 showed a severe loss of activity and CYP17A1, as well as CYP21A2 activities, were also lost by more than 95%. Loss of CYP2C9, CYP2C19, and CYP3A4 activities was observed for the R550W-POR. Predicted adverse effect on aromatase activity as well as a reduction in binding of NADPH was confirmed. Conclusions: Pathological effects due to POR R550W were identified, expanding the knowledge of molecular pathways associated with aromatase deficiency. Screening of the POR gene may provide a diagnosis in CAH without defects in genes for steroid metabolizing enzymes.