The following information may help to address your question:
You can find additional information on chromosome anomalies in general at the following Web sites.
The National Human Genome Research Institute, part of the National Institutes of Health (NIH), has developed a fact sheet on chromosome abnormalities, which may be helpful to you. To read this information, visit the link below.
MEDLINEplus, the National Library of Medicine Web site designed to direct you to information and resources that help you research your health questions, provides further information about chromosomes at the following link: