PITX2 and Axenfeld-Rieger syndrome: Three loci on chromosomes 4q25, 6p25, and 13q14 have been mapped for ARS.[1, 2] Of these, mutations in the forkhead winged/helix transcription factor, FOXC1 on chromosome 6p25[3] and the homeodomain protein PITX2 on chromosome 4q25[4] have been implicated as the cause of ARS.