A number of syndromes are linked to mutations in MED12 [5–7] including FG syndrome, type 1 (FGS1, or Opitz-Kaveggia syndrome); Lujan syndrome (LS, Lujan-Fryns syndrome, or intellectual disability, X-linked, with marfanoid habitus); X-linked Ohdo syndrome (XLOS; also called blepharophimoisis – intellectual disability syndrome, Maat-Kievit-Brunner (MKB) type) [8]; and Hardikar Syndrome (also known as cholestasis-pigmentary retinopathy-cleft palate syndrome). Here, MED12 is linked to Leigh syndrome.