In addition to BRCA1/2 deficiency, the amplification of EMSY[26] and deficiencies in PTEN[27], Fanconi Anemia genes [3], RAD genes and DNA repair genes involved in HR (including ATM, ATR and CHEK1/2) have also been identified to cause HR defects in human cancer [28]. The gene discussed is CHEK1; the disease is cancer.