[Page 319]Cri-du-chat syndrome is a genetic condition that is caused by part of the absence of a chromosome. In most cases, cri-du-chat syndrome is not caused by heredity but rather by an error in copying genes during reproduction. In 80% to 90% of cases, this deletion is from the paternal genes. A partial deletion of chromosome 5p causes the set of symptoms present in cri-du-chat syndrome and leads to the alternate name of 5p minus syndrome. In about 10% of cases, the syndrome is inherited from a parent with a translocation or some genetic material that has been rearranged. The parent likely has no symptoms, but because the genetic material has been moved on the chromosome, it is more susceptible to being copied incorrectly in ...