De novo pericentric inversion of chromosome 9 in congenital anomaly

Abstract

Purpose: The pericentric inversion of chromosome 9 is one of the most common structural balanced chromosomal variations and has been found in both normal populations and patients with various abnormal phenotypes and diseases. The aim of this study was to re-evaluate the clinical impact of inv(9)(p11q13).

Materials and methods: We studied the karyotypes of 431 neonates with congenital anomalies at the Pediatric Clinic in Ajou University Hospital between 2004 and 2008 and retrospectively reviewed their clinical data.

Results: Chromosomal aberrations were detected in 60 patients (13.9%). The most common type of structural abnormality was inv(9)(p11q13), found in eight patients. Clinical investigation revealed that all eight cases with inv(9)(p11q13) had various congenital anomalies including: polydactyly, club foot, microtia, deafness, asymmetric face, giant Meckel's diverticulum, duodenal diaphragm, small bowel malrotation, pulmonary stenosis, cardiomyopathy, arrhythmia, and intrauterine growth restriction. The cytogenetic analysis of parents showed that all of the cases were de novo heterozygous inv(9)(p11q13).

Conclusion: Since our results indicate that the incidence of inv(9)(p11q13) in patients with congenital anomalies was not significantly different from the normal population, inv(9)(p11q13) does not appear to be pathogenic with regard to the congenital anomalies. Some other, to date unknown, causes of the anomalies remain to be identified.

Fig. 1

GTG-banded karyotypes of the lymphocytes from patients with pericentric inversion of chromosome 9. The constitutional karyotypes of cases 3 and 8 were 46,XY, inv(9)(p11q13) and 46,XX, inv(9)(p11q13), respectively. No other chromosomal aberrations were detected in either case. GTG, G-bands by trypsin using Giemsa.

Fig. 2

Clinical and radiological features of patients with de novo inv(9)(p11q13). (A) Thumb duplication is seen on standard X-ray of one female newborn. (B) Barium filled the large cystic mass of the distal part of the ileum (arrow). Pathology specimen demonstrates the size of the giant Meckel's diverticulum. (C) Dilated duodenal bulb (arrowhead) and the obstructed lower portion of the duodenum (asterisk) is seen on the upper gastrointestinal study of one male newborn with a duodenal diaphragm and small bowel malrotation. (D) Cardiomegaly is seen on the standard chest X-ray and a prominent club foot is also present in one female newborn with congenital arrhythmia. (E) External auditory canal of the right ear is absent on three-dimensional reconstruction images of the computed tomography in one female newborn with unilateral microtia.