Complete trisomy 9 in two liveborn infants

suMMARY 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. Trisomy of chromosome 9 in its entirety appears to be a rare abnormality in liveborn infants. Complete trisomy 9 is used to indicate trisomy for the entire chromosome without evidence of mosaicism. Trisomy 9 mosaicism refers to the presence of both trisomy 9 and normal cells. Although a number of abortuses with trisomy 9 have been reported,1 2 only three liveborn infants with this chromosome abnormality have been described.-6 We now report Received for publication 25 November 1980 two unrelated newborn infants with multiple congenital malformations in whom trisomy for chromosome 9 was found. The similarity of clinical features in these infants is indicative of a distinct phenotype associated with trisomy 9. Case reports CASE 1 This term male infant (fig 1), born to a 17-year-old primigravida, was delivered by caesarian sectio