Array comparative genomic hybridization in prenatal diagnosis: another experience

Etiologic diagnosis of multiple congenital abnormalities (MCAs) is often lacking. Large chromosome abnormalities can be detected by conventional cytogenetic methods, but more subtle chromosome micro-rearrangements and/or de novo abnormalities require multi-FISH analysis, which is hampered by the amount of material available in prenatal testing.

We used the comparative genomic hybridization (CGH) array, Genosensor Array 300, to screen for classic microdeletion syndromes and subtelomeric rearrangements in 39 consecutive fetuses with MCAs, after termination of pregnancy, in a prospective study. Thirty-seven of them had a normal karyotype, and two had a de novo unbalanced karyotype that could not be characterized with conventional cytogenetic methods.

Two de novo unbalanced karyotypes were characterized by array CGH, and four additional abnormalities were diagnosed: an unbalanced inherited cryptic translocation, a deletion in band 22q11.2, a 1p36 deletion, and a 6p12.1-21.2 duplication.

Chromosomal imbalances were therefore detected and/or characterized in 6 of 39 (15.4%) fetuses, indicating the value of routine array CGH in cases of MCAs and in uncharacterized chromosome rearrangements. Extension to all prenatal diagnoses may be warranted when copy number variation is identified and all FISH probes are commercially available.