NR5A1 and alternating hemiplegia of childhood: There are five major genetic causes of AHC: 1) X-linked AHC (gene: DAX-1/NROB1, chromosomal location: Xp21.3-p21.2), 2) SF-1-linked AHC (gene: SF-1/NR5A1, chromosomal location: 9q33), 3) autosomal recessive AHC (gene: unknown), 4) IMAGe syndrome (gene: unknown), 5) ACTH insensitivity: triple A syndrome (gene: AAAS, chromosomal location: 12q13) (Table 2).