Steroid hormones are essential for the body to function properly. 11beta-hydroxylase deficiency is a rare genetic disorder that disrupts the production of steroid hormones. We have studied a patient with this deficiency and have identified a structural anomaly in the CYP11B1 gene in this family, which is particularly complicated to identify: the region of the DNA where the gene is located is partially inverted (oriented paradoxically in the opposite direction), making it non-functional. An appropriate and specialized analysis strategy is required to find this type of inverted gene, and thus provide a quality genetic information and appropriate cares to families. It is the first to be identified in this disease. (By Clément JANOT, Biologiste, PharmD, PhD student, https://jmg.bmj.com/content/early/2025/08/17/jmg-2025-110880 )