Original research article INTRODUCTIONConventional karyotyping has been considered the gold standard for routine prenatal genetic diagnosis for many decades now, allowing for microscopic visualization and inspection of chromosomes and thus detection of numerical and structural chromosomal rearrangements. The main limitations are the resolution achieved by G-banding, which is limited to 5-10 Mb at best, and the requirement for cultured cells, needing a minimum of 8-10 days. The introduction of targeted methods of analysis such as fluorescence in situ hybridization (FISH) and multiplex ligation-dependent probe amplification (MLPA) overcome the time constraints and resolution limitations inherent to karyotyping but do not provide a genome-wide analysis.1 More recently, molecular karyotyping using genomic microarrays has reached mainstream use in the postnatal diagnostic setting, providing a genome-wide screen for genomic imbalances at a far superior resolution to karyotyping.2 A number of studies have demonstrated the feasibility of prenatal diagnosis by genomic arrays using a variety of platforms, 3-7 but challenges remain in applying high-resolution genomic arrays to prenatal diagnosis. 6,8,9 One of the major ethical issues often raised is how to deal with variants of uncertain significance (VOUS) or risk loci, the detection of which leads to additional challenges for genetic counseling of parents. Furthermore, array analysis may reveal an imbalance for known "risk loci" where the future penetrance is uncertain or may be associated with variable expression. The penetrance risks for a number of recurrent copy-number variations (CNVs) have been estimated based on the frequencies in patients and controls. [10][11][12] However, although it is possible to calculate a populationbased risk, it is impossible in the prenatal setting to predict the phenotypic outcome in the child. Purpose:To evaluate the clinical utility of chromosomal microarrays for prenatal diagnosis by a prospective study of fetuses with abnormalities detected on ultrasound. Methods: Patients referred for prenatal diagnosis due to ultrasound anomalies underwent analysis by array comparative genomic hybridization as the first-tier diagnostic test.Results: A total of 383 prenatal samples underwent analysis by array comparative genomic hybridization. Array analysis revealed causal imbalances in a total of 9.6% of patients (n = 37). Submicroscopic copy-number variations were detected in 2.6% of patients (n = 10/37), and arrays added valuable information over conventional karyotyping in 3.9% of patients (n = 15/37). We highlight a novel advantage of arrays; a 500-kb paternal insertional translocation is the likely driver of a de novo unbalanced translocation, thus improving recurrence risk calculation in this family. Variants of uncertain significance were revealed in 1.6% of patients (n = 6/383). Conclusion:We demonstrate the added value of chromosomal microarrays for prenatal diagnosis in the presence of ultrasound anomalies. We advocate reporting back on...

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A case of a frontonasal malformation observed during the first trimester with three-dimensional ultrasonography and fetoscopy is reported. Absence of the nasal bone and a poorly characterized nose were visualized at 11 5/7 weeks by two-dimensional ultrasonography. Rendered three-dimensional ultrasound images revealed absence of the nasal bridge, widely spaced frontal bones and hypertelorism. Fetoscopy, performed at 12 3/7 weeks, confirmed the hypertelorism and showed a broad translucent nose with a flat nasal bridge. The final diagnosis of frontonasal malformation was made at autopsy after pregnancy termination. A review of prenatally diagnosed cases as well as the various syndromes having frontonasal malformation as a common denominator is presented.