Prenatal diagnosis of two de novo 4q35-qter deletions characterized by array-CGH.

Background: The 4q- syndrome is a well known genetic condition caused by a partial terminal or interstitial deletion in the long arm of chromosome 4. The great variability in the extent of these deletions and the possible contribution of additional genetic rearrangements, such as unbalanced translocations, lead to a wide spectrum of clinical manifestations. The majority of reports of 4q- cases are associated with large deletions identified by conventional chromosome analysis; however, the widespread clinical use of novel molecular techniques such as array comparative genomic hybridization (a-CGH) has increased the detection rate of submicroscopic chromosomal aberrations associated with 4q- phenotype.

Dual testing with QF-PCR and karyotype analysis for prenatal diagnosis of chromosomal abnormalities. Evaluation of 13,500 cases with consideration of using QF-PCR as a stand-alone test according to referral indications.

Objective: Evaluate the results obtained from Quantitative Fluorescent (QF)-PCR and conventional karyotype analysis to determine the advantages and disadvantages of dual testing in prenatal diagnosis.

Methods: From 1 June 2006 to 1 June 2010, dual testing by QF-PCR and karyotype analysis was performed in 13,500 prenatal samples. The rates of concordant results between the two methods were evaluated and the rates of clinically significant chromosomal abnormalities undetected by QF-PCR were assessed.