Prenatal diagnosis of mosaic trisomy 8q studied by ultrasound, cytogenetics, and array-CGH.

Mosaic trisomy 8, also known as Warkany syndrome, has a well-characterized constellation of phenotypic findings. Partial trisomy 8, including mosaic cases, has also been reported, with outcome and counseling dependent on the chromosomal segment involved and whether accompanied by partial aneuploidy for other chromosomes. We present a case of a fetus mosaic for trisomy of the entire long arm (q) of chromosome 8 without additional chromosomal aberrations. The diagnosis was made by amniocentesis performed following an 18 week sonogram that showed multiple fetal anomalies. Mosaicism for trisomy 8q was confirmed by routine karyotyping and fluorescent in situ hybridization (FISH) analysis. The case proved useful for testing the sensitivity of array comparative genomic hybridization (array-CGH) with respect to segmental trisomy in the presence of chromosomal mosaicism. The phenotype of this fetus, which appears to be the first reported case involving mosaic trisomy 8 for the entire q arm of the chromosome, is described and compared to previously reported cases involving partial trisomy 8q. © 2008 Wiley-Liss, Inc.