Assertion: chromosome's copy | /r/HasProperty | lethal
Facets:
value: for human embryos
type: TRANSITIVE-OBJECT
Source sentences:
text: For human embryos, extra copies of any chromosome are lethal, with the exceptions of chromosome 21, which produces Down syndrome; chromosomes 13 and 18, which lead to developmental disorders known as Patau and Edwards syndromes; and the X and Y sex chromosomes, extra copies of which may cause various disorders but are not usually lethal.