Use of subtelomeric fluorescence in situ hybridization in cytogenetic diagnosis

During the last few years there has been an increasing number of reports of chromosomal abnormalities identified by subtelomeric fluorescence in situ hybridization testing in children with unexplained mental retardation. As more children are identified with subtelomeric deletions, duplications, and cryptic unbalanced rearrangements by this testing, questions have arisen regarding the appropriate use of this new technology. A review of current knowledge regarding the clinical phenotypes seen in these patients as well as of newer information regarding the use of this new cytogenetic test in areas outside clinical genetics may help to determine which patients would benefit from its use.