CATCH-22 syndrome is a common genetic disorder with features of cardiac defect, abnormal face, thymic hypoplasia, cleft palate, and hypocalcemia, along with microdeletion at chromosome 22. This study is to report twelve Korean patients with CATCH-22 syndrome diagnosed by the fluorescent in situ hybridization (FISH) method.

Clinical features were analyzed according to the FISH result and the Southern blot analysis using new probes DGCR680 and pDH-1 was performed to correlate with the clinical findings and FISH results. Twelve patients were studied by FISH method and eight of them were studied by Southern blot analysis.

Seven patients had typical facial features for CATCH-22 syndrome, but five patients had equivocal face, although they were originally suspected to have the conotruncal face. The main cardiac lesion of eight patients were tetralogy of Fallot (TOF) and seven of them had pulmonary atresia. Two cases had other anomalies in the ventricular outflow tract, being common arterial trunk or pulmonary stenosis. Two cases had a patent arterial duct or atrial septal defect (ASD). All of twelve patients had positive result on FISH study. Among eight patients with positive FISH study, six cases were positive for Southern blot analysis.

We conclude that CATCH-22 syndrome has variable facial, cardiac and genetic features, and the combined use of probes is recommended for a more accurate diagnosis.