A group of rare chromosomal anomalies characterized by constitutional structural chromosomal rearrangements, including translocations, invertions, duplications and deletions, involving at least three breakpoints on two or more chromosomes. Individuals with such arrangements may display various phenotypes including cognitive impairment, congenital abnormalities and infertility, while some can also be phenotypically normal. Both de novo and familial forms are reported. [from
ORPHANET]