In humans, haploinsufficiency or mutations in GATA3, encoding a dual zinc finger transcription factor, cause the autosomal dominant disease known as hypoparathyroidism, deafness and renal dysplasia (HDR) syndrome or Barakat syndrome (Bilous et al., 1992; Van Esch et al., 2000). The gene discussed is GATA3; the disease is hypoparathyroidism.