Chromosome 9 inversion
- Inversion 9
Your QuestionA friend of mine is pregnant and had an amniocentesis. Her fetus was found to have a chromosome 9 inversion. Is there any disease associated with this abnormal chromosome finding?
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Chromosomes vary in size. Each chromosome has a constriction, called the centromere, at one point along its length dividing it into a shorter arm, called the p arm, and a longer arm, called the q arm. Chromosome tests allow us to take a closer look at the chromosomes and identify changes, such as missing or added pieces. To read more about chromosomes, click here.
One study reviewed the results of 652 chromosome studies on mid-trimester amniocentesis (16–18 weeks) during a 10-year period from January 1985 to February 1995. Of 652 patients, pericentric inversion of chromosome 9 was found in 27 cases. The indications for amniocentesis among these 27 patients included advanced maternal age, abnormal ultrasound findings, abnormal maternal serum screening tests, and family history of a child with a disability. Immediate evaluation of these infants after birth was normal in 24 and abnormal in 3; one had a low Apgar score at 1 and 5 min, one had bilateral capillary hemangioma over the eyelids, and one had a heart murmur and an irregular heart rhythm. The researchers concluded that inversion of chromosome 9 is associated with a normal outcome in the majority of cases.
However, it is important to discuss an inversion chromosome 9 found through amniocentesis with a genetics professional. This type of health care professional can help you understand the size and location of the inversion and the effect, if any, this finding may have on the fetus.
Genetics clinics are a source of information for individuals and families regarding genetic conditions, treatment, inheritance, and genetic risks to other family members. More information about genetic consultations is available from Genetics Home Reference. To find a genetics clinic, we recommend that you contact your primary healthcare provider for a referral.
The following online resources can help you find a genetics professional in your community:
- GeneTests has a searchable directory of US and international genetics and prenatal diagnosis clinics.
- The National Society of Genetic Counselors provides a searchable directory of US and international genetic counseling services.
- The American College of Medical Genetics has a searchable database of US genetics clinics.
- The University of Kansas Medical Center provides a list of US and international genetic centers, clinics, and departments.
- The American Society of Human Genetics maintains a database of its members, which includes individuals who live outside of the United States. Visit the link to obtain a list of the geneticists in your country, some of whom may be researchers that do not provide medical care.
- Chromosome Abnormalities. National Human Genome Research Institute Web site. 2007; http://www.genome.gov/11508982#6 . Accessed 7/11/2011.
- Chromosomes and Rare Chromosome Disorders in General. Unique. http://www.rarechromo.org/html/ChromosomesAndDisorders.asp. Accessed 3/16/2011.
- Ait-Allah AS, Ming PL, Salem HT, & Reece EA. The Clinical Importance of Pericentric Inversion of Chromosome 9 in Prenatal Diagnosis. Journal of Maternal-Fetal Investigation. 1997; 7(3):126-128. http://www.springerlink.com/content/6c1lvkqpng218v64/. Accessed 3/16/2011.
- Gardner and Sutherland. Chromosome Abnormalities and Genetic Counseling, 3rd Edition. NY, NY: Oxford University Press; 2004;