Often the genetic change involves a 5' (aminoterminal) stop variant in the gene and translation of a shorter protein with partial function, or a partial loss‐of‐function variant in the ligand‐like binding domain of NR0B1 (Figure 1A, 1).12 One recent review of adult men with PAI in a single UK centre identified two patients with X‐linked AHC due to partial loss‐of‐function variants in DAX‐1, suggesting that late‐onset X‐linked AHC may be underdiagnosed in the adult population (Figure 1B & 1).16 The gene discussed is NR0B1; the disease is alternating hemiplegia of childhood.