Inverted duplication 18q12.1-q22

Abstract

BACKGROUND: Partial duplications over the long arm of Chromosome 18 have been associated with congenital heart disease, multiple dysmorphism, seizure, growth retardation and developmental delay. Genotype-phenotype correlation, however, is still controversial, as is the association with the full Trisomy 18 phenotype. We report a Chinese infant with an inverted duplication involving a novel region within Chromosome 18q. CASE REPORT: The proposita was born to a nonconsanguineous healthy Chinese couple. Dysmorphism was noted and ventricular septal defect (VSD), secundum atrial septal defect (ASD), patent ductus arteriosus (PDA) as well as coarctation of aorta were detected. Karyotyping of the patient, followed by multicolour fluorescence in-situ hybridization and multicolour banding suggested an inverted duplication of 18q12.1 to q22 over the long arm of Chromosome 18. Array comparative genomic hybridization demonstrated a copy number gain between 18q12.1 and 18q22.1 (Genomic coordinates: Chr 18: 30273585-62939673) with an estimated size of 32.67- 32.74Mb. Maternal karyotype was normal, and that of the father was not available. DISCUSSION: The inverted duplication carried by our patient is to our knowledge, previously unreported. Features observed in the index patient were comparable to those described in patients with partial duplication involving and distal to 18q21. The absence of a classical Trisomy 18 phenotype in our patient also supported the hypothesis of proximal and distal critical regions in Edwards syndrome, with the proposed distal region lying within 18q22.3-qter.