NCIt definition : A chromosomal abnormality characterized by the presence of three copies of genetic
material for chromosome 13, instead of the normal two. It leads to a variety of abnormalities
that include mental retardation, microcephaly, low-set ears, eye structural defects,
polydactyly, and limb abnormalities.;
Alternative definition : ACC/AHA: A chromosomal abnormality consisting of the presence of part or all of a
third copy of chromosome 13 in somatic cells.;