Three other rare recessive X-linked disorders include Joubert syndrome 10 (JBTS10, MIM 300804) [5–7], Simpson-Golabi-Behmel syndrome, type 2 (SGBS2, MIM 300209) [8], and a severe retinitis pigmentosa (RP32, MIM 300424) [9]. Here, OFD1 is linked to Down syndrome.