The McDonough syndrome is a "new" MCA/MR syndrome which was found in 3 children (1 girl, 2 boys) of non-consanguineous parents. The affected children were mentally retarded (IQ 47--67) and had congenital heart defect, sternal deformity, kyphosis and craniofacila anomalies (anteverted auricles, upward slanted palpebral fissures, squint); cryptorchidism was present in the 2 boys. In addition a possible VFDP is postulated as the explanation for similar features in affected and unaffected siblings and parents. However, the McDonough syndrome may be an autosomal recessive trait with minor manifestations in heterozygotes. The klinefelter syndrome in one affected boy and a 46,XY/47,XXY chromosome constitution in the father was a coincidental finding.