Genotyping for CYP450 polymorphism has primarily been used for research purposes or clinical drug trials. Recently, the FDA approved the first genotype test designed for use by physicians to guide the selection of medications metabolized by CYP450 enzymes. The Amplichip CYP450 test is a DNA microarray that can detect 29 polymorphisms of CYP2D6 and two polymorphisms of CYP2C19 using a blood sample. 33 Roche Diagnostics currently charges laboratories $500 per test, and most major insurance companies do not cover the cost. 34 Although there is evidence of a link between adverse effects and polymorphisms coding for reduced CYP450 activity, large prospective clinical trials are needed to determine whether use of genotyping in clinical practice is cost-effective and improves clinical outcomes by preventing adverse drug effects or identifying poor responders. 5 , 7 , 35 , 36
Cells of the zona fasciculata and zona reticularis lack aldosterone synthase (CYP11B2) that converts corticosterone to aldosterone, and thus these tissues produce only the weak mineralocorticoid corticosterone. However, both these zones do contain the CYP17A1 missing in zona glomerulosa and thus produce the major glucocorticoid, cortisol. Zona fasciculata and zona reticularis cells also contain CYP17A1, whose 17,20-lyase activity is responsible for producing the androgens, dehydroepiandosterone (DHEA) and androstenedione. Thus, fasciculata and reticularis cells can make corticosteroids and the adrenal androgens, but not aldosterone.