Complete trisomy 9 in two liveborn infants.

Two unrelated newborn infants with multiple malformations were found to have complete trisomy 9 in all cells examined. In both, the phenotype was similar, consisting of characteristic facial appearance (microphthalmia, bulbous nose, micrognathia, cleft palate, low set ears), skeletal abnormalities (dislocated joints, flexion contractures of the fingers), cardiovascular malformations (persistent left superior vena cava, ventricular septal defect), hypoplastic genitalia, renal anomalies, and central nervous system malformations. Both died during the first few hours of life. Comparison of these two infants with the previously reported cases reveals a consistent pattern of malformations and very short survival associated with trisomy 9. These cases illustrate the importance of doing chromosome studies on infants with congenital malformations dying in the newborn period and the usefulness of such studies in counselling parents regarding the risk of recurrence.