Expansion in size of a terminal deletion: a paradigm shift for parental follow-up studies

Abstract

Traditional parental follow-up studies would have not identified this expansion, but would have rather classified the deletion in the daughter as either de novo or benign. Only by sizing the deletion by array comparative genomic hybridisation in both the mother and the daughter was the expansion recognised. Previous assumptions about chromosome behaviour suggest that this phenomenon may have been easily missed in other cases of chromosomal deletions. Therefore, this case illustrates the need for more comprehensive analyses of parental chromosome structure when characterising an abnormality in a child.