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Inherited Disorders and Birth Defects

My niece is missing her 13th chromosome



Hi, My question is that my niece is missing her 13th chromosome. What does this mean for her? The doctors in her case seem to be unsure of what will happen to her and I was wondering where I could get some more info on the topic. What does it mean to be missing a chromosome? Are there some other cases to compare to? What is the possible out come, best and worst case. Thank you for your time. Sincerely.


I am assuming that your niece has a deletion of part of one of her # 13 chromosomes. A deletion is caused by a chromosome break and then loss of genetic material. It can occur anywhere along the chromosome and can occur with any chromosome. What types of abnormalities would be seen - the phenotype - would depend on what genes were located on the part of the chromosome that was missing and how much of the chromosome material was missing. Chromosome abnormalities, including deletions, usually lead to changes in growth - usually small, possibility of major birth defects, minor malformations and dysmorphic features and developmental delay or mental retardation.

The specific types of problems your niece will have would be based on what part of the chromosome is missing. Hopefully your niece’s parents have had the opportunity to discuss this diagnosis with a geneticist or genetic counselor. If not, I would recommend that they talk to their doctor about speaking to a geneticist. If the genetic counselor knows that what part of chromosome 13 is missing, then she or he could provide your family with more information about what has been reported for that specific deletion.

Your family can locate a genetics center near them at the National Society of Genetic Counselors’ Resource Center at the website below.

Related Resources:

National Society of Genetic Counselors Resource Center

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Response by:

Anne   Matthews, RN, PhD Anne Matthews, RN, PhD
Associate Professor of Genetics
School of Medicine
Case Western Reserve University