Complete trisomy 9 in a term fetus: A case report

The Journal of Maternal-Fetal Medicine 7:247–249 (1998)

Complete Trisomy 9 in a Term Fetus: A Case Report Daniel Roshanfekr, MD,* Cecilia Dahl-Lyons, MD, Eva Pressman, MD, Serdar Ural, MD, and Karin Blakemore, MD

Department of Gynecology and Obstetrics, The Johns Hopkins University School of Medicine, Baltimore, Maryland

Abstract

Complete trisomy 9 was diagnosed in a 35-week fetus by amniocentesis. Several sonograms had revealed only a two-vessel cord and intrauterine growth restriction. No other abnormalities were noted. A stillborn infant was delivered at 37 weeks gestation after induction of labor. J. Matern.–Fetal Med. 7:247–249, 1998. r 1998 Wiley-Liss, Inc.

Key words: complete trisomy 9; two vessel cord; IUGR; ultrasound

INTRODUCTION Complete trisomy 9 is rare. Most such cases result in first trimester spontaneous abortions [1], wherein it compromises only 2.7% of trisomic cases. It is rarely seen at near or term. Associated abnormalities in fetuses surviving beyond the first trimester include craniofacial, cardiac, skeletal, and genitourinary malformations [2–6]. We encountered an unusual case of complete trisomy 9 in the late third trimester in which the only ultrasonographic findings noted antenatally were a two-vessel cord and intrauterine growth restriction (IUGR). CASE REPORT A 28-year-old Oriental gravida 1, para 0 underwent a routine complete fetal anomaly scan at 20 weeks gestation due to an abnormal maternal serum triple marker screen (AFP 0.6 M.o.M., estriol 0.6 M.o.M., hCG 0.2 M.o.M.), which revealed a two-vessel umbilical cord; no other abnormalities were noted. The patient was offered amniocentesis for fetal karyotype, given her triple screen analytes, which were suggestive of possible trisomy 18 in her fetus, and she declined. A fetal echocardiogram was performed, which was unremarkable. Two subsequent sonograms were performed because of a lag in fundal height to evaluate fetal growth, which revealed no additional abnormalities except that the estimated fetal weights were at the 21st percentile at 31 weeks gestation and at 3rd percentile at 35 weeks gestation. At 36.6 weeks gestation, the fetal weight was at 3rd percentile for gestational age. The femur length (FL) to biparietal diameter (BPD) ratio was 0.80 (normal 0.71– 0.87). FL to abdominal circumference (AC) ratio was 0.25 r 1998 Wiley-Liss, Inc.

(normal 0.20–0.24). Head circumference (HC) to AC ratio was 1.13 (normal 0.92–1.11). The systolic/diastolic ratio was elevated at 3.55 on the 35-weeks scan. The amniotic fluid volume was normal throughout gestation. After further counseling, the parents elected to have fetal karyotyping, which was carried out by amniocentesis and revealed complete trisomy 9 in all cells examined. The patient opted for labor induction without fetal monitoring and delivered via assisted breech extraction a fresh stillborn female infant. We cannot clearly explain the cause of death, but one can speculate acute fetal distress to be the likely cause. Gross examination revealed very mild micrognathia (Figs. 1 and 2) and that the hands were held loosely clenched in a peculiar way, with fingers flexed at the distal interphalangeal joints. Autopsy revealed a two-vessel cord; examination of the internal organs demonstrated normal anatomic orientation and development. There were no radiographic abnormalities present. Both parent had normal peripheral lymphocyte karyotypes. RESULTS AND DISCUSSION Trisomy 9 was first described by Feingold and Atkins [7] in 1973. This rare chromosomal abnormality may be present in one of three ways: nonmosaic complete trisomy 9, mosaic trisomy 9, and trisomy 9p syndromes. There are multiple

*Correspondence to: Daniel Roshanfekr, M.D., Dept. of Gynecology and Obstetrics, 600 North Wolfe Street, Houck 228, Baltimore, MD 21287-1228. Received 18 February 1998; revised 2 June 1998; accepted 15 June 1998

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Fig. 1. Profile view: note very mild micrognathia.

phenotypic features associated with trisomy 9. Wooldridge [2] reviewed a large series of cases published to date and found craniofacial anomalies of some kind to exist in all cases. Other common anomalies included cardiac, central nervous system, genitourinary, and skeletal anomalies. Growth retardation is a common nonspecific finding [8,9]. Of liveborns, only 3 of 12 (25%) lived beyond 7 days and 7 of 12 (58%) had cesarean delivery [1]. To our knowledge, there is no reported long-term survival for fetuses with complete trisomy 9. Currently there is no report of an association of any abnormal maternal serum triple screen pattern with trisomy 9. In our patient the triple screen was abnormal with low AFP, low estriol, and low hCG, a pattern also seen with trisomy 18. Future studies are needed to determine whether there is any associated triple screen pattern with trisomy 9. Cases of complete trisomy 9 that have been ascertained in amniocytes may be expected to be confirmed upon cytogenetic analysis of fetal tissues. However, there are multiple reports in the literature of mosaic trisomy 9 detected on amniocytes, but subsequently not confirmed in the fetus or newborn. All prenatally diagnosed cases of complete trisomy 9 reported to date have been associated with multiple anomalies found on obstetrical ultrasound examination and then confirmed at autopsy. Our case appears to be unique in that the only abnormal findings were a two-vessel umbilical cord, intrauterine growth retardation, and very mild micrognathia in this fetus with complete trisomy 9.

Fig. 2. Full view: note normal findings.

TRISOMY 9

When severe intrauterine growth restriction is diagnosed in the absence of an associated obstetrical problem or maternal disorder, fetal karyotyping should be offered antenatally. When the results are abnormal, obstetrical and neonatal management may be altered according to the parents’ wishes. This is particularly true for the growth of retarded fetuses with a chromosomal abnormality, since many will exhibit fetal distress in the antepartum or intrapartum periods. Many patients opt not to have a cesarean section for fetal distress, especially if the condition is lethal, as is complete trisomy 9 [2–6]. The literature indicates that a fetal chromosome abnormality is found 20%, 15.4%, and 25% of third trimester pregnancies having severe IUGR (below percentile for gestational age) and severely decreased, normal, and increased amniotic fluid volume, respectively [10]. These figures may be higher if pregnancies with hypertension or other complications that may be causative of IUGR are excluded. When severe IUGR is encountered with severely decreased amniotic fluid volume and there are no maternal or obstetrical factors that might explain these findings, the diagnosis of fetal triploidy should be considered. Like trisomy 9, rarely does a triploid fetus reach full term. Similarly, however, when the amniotic fluid is normal or increased, a fetal karyotypic abnormality may be encountered. Offering prompt fetal cytogenetic analysis in the third trimester fetus with severe unexplained IUGR is an essen-

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tial component of obstetrical management in such cases. Such knowledge affords the patient and her family the opportunity for informed decision making and optimal perinatal management. REFERENCES 1. McDuffie RS: Complete trisomy 9: Case report with ultrasound findings. Am J Perinatol 2:80–84, 1994. 2. Woolridge J, Zunich J: Trisomy 9 syndrome: Report of a case with Crohns disease and review of the literature. Am J Med Genet 56:258–269, 1995. 3. Benaceraf BR, Pauker S, Ceunde BJ, Bieber FR: Prenatal sonography in trisomy 9. Prenatal Diagnosis 12:175–181, 1992. 4. Saura R, Tragore W, Taine L, Wen EZ, Rou XD, Maugey-Laulom B, Ruffie M, Vergnaud A, Horovitz J: Prenatal diagnosis trisomy 9 six cases and a review of the literature. Prenatal Diag 15:609–614, 1995. 5. Arnold GL, Kirby SR, Stern PT, Sawyer JR: Trisomy 9: Review and report of two new cases. Am J Med Genet 56:252–257, 1995. 6. Golden JA, Schene WC: Central nervous system malformation in trisomy 9. J Neuropathol Experiment Neurol 52:71–77, 1995. 7. Feingold M, Atkins L: A case of trisomy 9. J Med Genet 10:184–187, 1973. 8. Mace SE, MacIntyre MN, Turk KB, Johnson WE: The trisomy 9 syndrome: Multiple congenital anomaly and unusual pathological findings. J Pediatr 92:446–448, 1978. 9. Chitayut D, Hodgkihson K, Luke A, Winsor E, Rose T: Prenatal diagnosis and fetopathological findings in five fetuses with trisomy 9. Am J Med Genet 56:247–251, 1995. 10. Chew S, Anandakumar C: Incidence of chromosomal abnormalities in 153 pregnancies with ultrasound detected fetal abnormalities. Singapore Med J 37:595–597, 1996.