NR5A1 and alternating hemiplegia of childhood: If AHC is diagnosed in a female, it is important to establish whether there is a normal female karyotype, as females with 46XY karyotypes or Turner syndrome can manifest X-linked conditions.14–17 In the presence of a 46XX karyotype, autosomal recessive causes of AHC (such as StAR, SF1, (NR5A1) mutations) should be considered.18, 19