The so-called "conotruncal anomaly face syndrome" (CTAFS) is characterized by a peculiar facial appearance associated with congenital heart disease (CHD), especially cardiac outflow tract defects such as tetralogy of Fallot (TOF), double outlet right ventricle (DORV), and truncus arteriosus (TAC). CTAFS and the DiGeorge anomaly (DGA) have many similar phenotypic characteristics, suggesting that they share a common cause. In many cases DGA is known to be associated with monosomy for a region of chromosome 22q11.2. Fifty CTAFS patients and 10 DGA patients, 11 parents couples and 10 mothers of CTAFS patients, and 3 parents couples and 2 mothers of DGA patients were examined by fluorescent in situ hybridization (FISH) using the N25 (D22S75) DGCR probe (Oncor). Monosomy for a region of 22q11.2 was found in 42 CTAFS, 9 DGA, 4 mothers, and 1 father who had CTAF without CHD. The remaining 8 CTAFS patients 1 DGA patient and 1 mother who had questionable CTAF without CHD, showed no such chromosome abnormality. For the control, 60 patients who had CHD without CTAF or other known malformation syndromes were examined and had no deletion of 22q11.2. Therefore, we conclude that CTAFS is a part of the CATCH 22 syndrome; cardiac defects, abnormal faces, thymic hypoplasia, cleft palate, and hypocalcemia (CATCH) resulting from 22q11.2 deletions.