In contrast, the lyase step of CYP17A1 is mainly active in the adrenal zona reticularis, and the observed inverse correlation between CSF androstanes and androgen production in this region may reflect declining zona reticularis function as MS progresses (see [19,38] and http://biogps.org/#goto=genereport&id=1586, accessed on 18 February 2025). This evidence concerns the gene CYP17A1 and myeloid sarcoma.