A prenatal missed diagnosed case of submicroscopic chromosomal abnormalities by karyotyping: the clinical utility of array-based CGH in prenatal diagnostics

BACKGROUND: Array-based comparative genomic hybridization possesses a number of significant advantages over conventional cytogenetic and other molecular cytogenetic techniques, providing a sensitive and comprehensive detection platform for unexpected imbalances in the genome wide. CASE PRESENTATION: The newborn proband, demonstrated with craniofacial dysmorphism and multiple malformations, was born to a family with spontaneous abortions. This pregnancy was uneventful, except the prenatal ultrasound examination showed an increased nuchal translucency at 12(+) weeks of gestation. Cytogenetics revealed an apparently normal karyotype, and the couple decided to continue the pregnancy. Array-based CGH analysis was applied to the affected infant, identified a combination of 18p deletion and 7q duplication. Further study indicates that the unbalanced translocation was inherited from a balanced translocation carrier parent. CONCLUSIONS: In review of the case, several overlooked points leading to the missed diagnosis should be discussed and certain quality control strategies should be adopted to avoid similar problems in the future. Array-based CGH and karyotyping techniques are complemented by diverse detection spectrum and resolutions, and a combination of these methods could help providing optimal genetic diagnosis. Given that the array-CGH analysis will not introduce additional risk to patients, it is reasonable to recommend those already undergoing invasive testing should take array-based CGH as an adjunct to conventional cytogenetic tests and other molecular cytogenetic analysis.